realtek: enable basic config for cpufreq framework

A new clock driver makes more sense if it can be used from consumers
like cpufreq.  Before we enable the driver we must tell the config that
the RTL838X and RTL839X targets allow CPU frequency changing.

Even though these targets currently rely on the CPU's internal R4K
timer, MIPS_EXTERNAL_TIMER is selected to allow for CPU frequency change
testing. The Realtek timers, which are clocked by the Lexra bus, still
need to be supported and used in order to provide correct wall times
when reclocking the CPU.

Signed-off-by: Markus Stockhausen <[email protected]>
[add paragraph about MIPS_EXTERNAL_TIMER to commit message]
Signed-off-by: Sander Vanheule <[email protected]>

target/linux/realtek/patches-5.10/300-mips-add-rtl838x-platform.patch

@@ -10,7 +10,7 @@
  platform-$(CONFIG_SGI_IP28)		+= sgi-ip22/
 --- a/arch/mips/Kconfig
 +++ b/arch/mips/Kconfig
-@@ -1037,8 +1037,58 @@ config NLM_XLP_BOARD
+@@ -1037,8 +1037,62 @@ config NLM_XLP_BOARD
  	  This board is based on Netlogic XLP Processor.
  	  Say Y here if you have a XLP based board.
  
@@ -38,14 +38,18 @@
 +config RTL838X
 +	bool "Realtek RTL838X based platforms"
 +	depends on RTL83XX
++	select CPU_SUPPORTS_CPUFREQ
 +	select CSRC_R4K
 +	select CEVT_R4K
++	select MIPS_EXTERNAL_TIMER
 +
 +config RTL839X
 +	bool "Realtek RTL839X based platforms"
 +	depends on RTL83XX
++	select CPU_SUPPORTS_CPUFREQ
 +	select CSRC_R4K
 +	select CEVT_R4K
++	select MIPS_EXTERNAL_TIMER
 +	select SYS_SUPPORTS_MULTITHREADING
 +
 +config RTL930X