Revert "arm64: Mark __stack_chk_guard as __ro_after_init"

This reverts commit 69e450b1 which is
commit 9fcb2e93 upstream.

Turns out to break the build when CONFIG_CC_STACKPROTECTOR=y.

Reported-by: Hans-Christian Egtvedt <hegtvedt@cisco.com>
Link: https://lore.kernel.org/r/DM5PR11MB001226B8D03B8CC8FA093AC6DDB09@DM5PR11MB0012.namprd11.prod.outlook.com


Cc: Dan Li <ashimida@linux.alibaba.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

arch/arm64/kernel/process.c

@@ -55,7 +55,7 @@
 
 #ifdef CONFIG_CC_STACKPROTECTOR
 #include <linux/stackprotector.h>
-unsigned long __stack_chk_guard __ro_after_init;
+unsigned long __stack_chk_guard __read_mostly;
 EXPORT_SYMBOL(__stack_chk_guard);
 #endif