kernel: drop mips highmem offset start overrides

The maximum offset that can be supported is 0x20000000
Do not override it to to something bigger than that on MT7621, as that could
cause issues based on the fixed memory mappings. This makes the last 64 MB
RAM unusable on MT7621 devices with 512 MB but avoids incurring a heavy
performance hit

Fixes: cd2b74e01e8d ("ramips: mt7621: disable highmem support and remove highmem offset patch")
Signed-off-by: Felix Fietkau <[email protected]>

target/linux/generic/pending-5.15/307-mips_highmem_offset.patch

@@ -1,19 +0,0 @@
-From: Felix Fietkau <[email protected]>
-Subject: kernel: adjust mips highmem offset to avoid the need for -mlong-calls on systems with >256M RAM
-
-Signed-off-by: Felix Fietkau <[email protected]>
----
- arch/mips/include/asm/mach-generic/spaces.h | 2 +-
- 1 file changed, 1 insertion(+), 1 deletion(-)
-
---- a/arch/mips/include/asm/mach-generic/spaces.h
-+++ b/arch/mips/include/asm/mach-generic/spaces.h
-@@ -46,7 +46,7 @@
-  * Memory above this physical address will be considered highmem.
-  */
- #ifndef HIGHMEM_START
--#define HIGHMEM_START		_AC(0x20000000, UL)
-+#define HIGHMEM_START		_AC(0x10000000, UL)
- #endif
- 
- #endif /* CONFIG_32BIT */

target/linux/generic/pending-6.1/307-mips_highmem_offset.patch

@@ -1,19 +0,0 @@
-From: Felix Fietkau <[email protected]>
-Subject: kernel: adjust mips highmem offset to avoid the need for -mlong-calls on systems with >256M RAM
-
-Signed-off-by: Felix Fietkau <[email protected]>
----
- arch/mips/include/asm/mach-generic/spaces.h | 2 +-
- 1 file changed, 1 insertion(+), 1 deletion(-)
-
---- a/arch/mips/include/asm/mach-generic/spaces.h
-+++ b/arch/mips/include/asm/mach-generic/spaces.h
-@@ -46,7 +46,7 @@
-  * Memory above this physical address will be considered highmem.
-  */
- #ifndef HIGHMEM_START
--#define HIGHMEM_START		_AC(0x20000000, UL)
-+#define HIGHMEM_START		_AC(0x10000000, UL)
- #endif
- 
- #endif /* CONFIG_32BIT */

target/linux/ramips/patches-5.15/120-highmem-start-offset.patch

@@ -1,19 +0,0 @@
-From: Felix Fietkau <[email protected]>
-Date: Mon Jul 24 13:29:13 CEST 2023
-Subject: [PATCH] mips: ralink: increase highmem start
-
-Increase highmem start address in order to support devices with 512 MB memory
-and MT7621 SoC
-
-Signed-off-by: Felix Fietkau <[email protected]>
----
---- a/arch/mips/include/asm/mach-ralink/spaces.h
-+++ b/arch/mips/include/asm/mach-ralink/spaces.h
-@@ -5,6 +5,7 @@
- #define PCI_IOBASE	_AC(0xa0000000, UL)
- #define PCI_IOSIZE	SZ_16M
- #define IO_SPACE_LIMIT	(PCI_IOSIZE - 1)
-+#define HIGHMEM_START   _AC(0x24000000, UL)
- 
- #include <asm/mach-generic/spaces.h>
- #endif