arm64: support keyctl() system call in 32-bit mode

As is the case for a number of other architectures that have a 32-bit
compat mode, enable KEYS_COMPAT if both COMPAT and KEYS are enabled.
This allows AArch32 programs to use the keyctl() system call when
running on an AArch64 kernel.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index a39029b..f21e9a7 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -1063,6 +1063,10 @@
 	def_bool y
 	depends on COMPAT && SYSVIPC
 
+config KEYS_COMPAT
+	def_bool y
+	depends on COMPAT && KEYS
+
 endmenu
 
 menu "Power management options"