arm64: mops: don't disable host MOPS instructions from EL2

To allow nVHE host EL0 and EL1 to use FEAT_MOPS instructions, configure
EL2 to not cause these instructions to be treated as UNDEFINED. A VHE
host is unaffected by this control.
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
Link: https://lore.kernel.org/r/20230509142235.3284028-6-kristina.martsenko@arm.comSigned-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/include/asm/kvm_arm.h

@@ -94,7 +94,7 @@
 #define HCR_HOST_VHE_FLAGS (HCR_RW | HCR_TGE | HCR_E2H)
 
 #define HCRX_GUEST_FLAGS (HCRX_EL2_SMPME)
-#define HCRX_HOST_FLAGS 0
+#define HCRX_HOST_FLAGS (HCRX_EL2_MSCEn)
 
 /* TCR_EL2 Registers bits */
 #define TCR_EL2_RES1		((1U << 31) | (1 << 23))