arm64/sysreg: Add SYS_FIELD_GET() helper

Add a SYS_FIELD_GET() helper to match SYS_FIELD_PREP(), providing a
simplified interface to FIELD_GET() when using the generated defines
with standardized naming.
Signed-off-by: Mark Brown <broonie@kernel.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20220704170302.2609529-5-broonie@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

arch/arm64/include/asm/sysreg.h

@@ -1324,6 +1324,9 @@
 
 #endif
 
+#define SYS_FIELD_GET(reg, field, val)		\
+		 FIELD_GET(reg##_##field##_MASK, val)
+
 #define SYS_FIELD_PREP(reg, field, val)		\
 		 FIELD_PREP(reg##_##field##_MASK, val)