KVM: arm64: add SYS_DESC()

This patch adds a macro enabling us to initialise sys_reg_desc
structures based on common sysreg encoding definitions in
<asm/sysreg.h>. Subsequent patches will use this to simplify the KVM
code.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Christoffer Dall <christoffer.dall@linaro.org>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: kvmarm@lists.cs.columbia.edu

arch/arm64/kvm/sys_regs.h

@@ -147,4 +147,9 @@ const struct sys_reg_desc *find_reg_by_id(u64 id,
 #define CRm(_x) 	.CRm = _x
 #define Op2(_x) 	.Op2 = _x
 
+#define SYS_DESC(reg)					\
+	Op0(sys_reg_Op0(reg)), Op1(sys_reg_Op1(reg)),	\
+	CRn(sys_reg_CRn(reg)), CRm(sys_reg_CRm(reg)),	\
+	Op2(sys_reg_Op2(reg))
+
 #endif /* __ARM64_KVM_SYS_REGS_LOCAL_H__ */