x86: add missing configuration

Added settings:
        x86: CONFIG_MITIGATION_ITS=y [1]

[1] https://web.git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=linux-6.6.y&id=f7ef7f6ccf2bc3909ef5e50cbe9edf2bac71e1bd
Co-authored-by: Mieczyslaw Nalewaj <[email protected]>
Signed-off-by: Mieczyslaw Nalewaj <[email protected]>
Signed-off-by: Goetz Goerisch <[email protected]>
Link: https://github.com/openwrt/openwrt/pull/18924
Signed-off-by: Robert Marko <[email protected]>

target/linux/x86/config-6.6

@@ -243,6 +243,7 @@ CONFIG_MICROCODE_INITRD32=y
 CONFIG_MICROCODE_LATE_FORCE_MINREV=y
 CONFIG_MICROCODE_LATE_LOADING=y
 CONFIG_MIGRATION=y
+CONFIG_MITIGATION_ITS=y
 CONFIG_MITIGATION_RFDS=y
 CONFIG_MITIGATION_SPECTRE_BHI=y
 # CONFIG_MK6 is not set