riscv: add ISA extension parsing for Zfa

Add parsing for Zfa ISA extension [1] which were ratified in commit
056b6ff467c7 ("Zfa is ratified") of riscv-isa-manual[2].

Link: https://drive.google.com/file/d/1VT6QIggpb59-8QRV266dEE4T8FZTxGq4/view [1]
Link: https://github.com/riscv/riscv-isa-manual/commits/056b6ff467c7 [2]
Signed-off-by: Clément Léger <cleger@rivosinc.com>
Reviewed-by: Evan Green <evan@rivosinc.com>
Link: https://lore.kernel.org/r/20231114141256.126749-19-cleger@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

arch/riscv/include/asm/hwcap.h

@@ -83,6 +83,7 @@
 #define RISCV_ISA_EXT_ZIHINTNTL		68
 #define RISCV_ISA_EXT_ZVFH		69
 #define RISCV_ISA_EXT_ZVFHMIN		70
+#define RISCV_ISA_EXT_ZFA		71
 
 #define RISCV_ISA_EXT_MAX		128
 #define RISCV_ISA_EXT_INVALID		U32_MAX

arch/riscv/kernel/cpufeature.c

@@ -259,6 +259,7 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = {
 	__RISCV_ISA_EXT_DATA(zihintntl, RISCV_ISA_EXT_ZIHINTNTL),
 	__RISCV_ISA_EXT_DATA(zihintpause, RISCV_ISA_EXT_ZIHINTPAUSE),
 	__RISCV_ISA_EXT_DATA(zihpm, RISCV_ISA_EXT_ZIHPM),
+	__RISCV_ISA_EXT_DATA(zfa, RISCV_ISA_EXT_ZFA),
 	__RISCV_ISA_EXT_DATA(zfh, RISCV_ISA_EXT_ZFH),
 	__RISCV_ISA_EXT_DATA(zfhmin, RISCV_ISA_EXT_ZFHMIN),
 	__RISCV_ISA_EXT_DATA(zba, RISCV_ISA_EXT_ZBA),