riscv: Add X register names to gpr-nums

When encoding instructions it's sometimes necessary to set a
register field to a precise number. This is easiest to do using
the x<num> naming.
Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Signed-off-by: Anup Patel <anup@brainfault.org>

arch/riscv/include/asm/gpr-num.h

@@ -3,6 +3,11 @@
 #define __ASM_GPR_NUM_H
 
 #ifdef __ASSEMBLY__
+
+	.irp	num,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31
+	.equ	.L__gpr_num_x\num, \num
+	.endr
+
 	.equ	.L__gpr_num_zero,	0
 	.equ	.L__gpr_num_ra,		1
 	.equ	.L__gpr_num_sp,		2
@@ -39,6 +44,9 @@
 #else /* __ASSEMBLY__ */
 
 #define __DEFINE_ASM_GPR_NUMS					\
+"	.irp	num,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31\n" \
+"	.equ	.L__gpr_num_x\\num, \\num\n"			\
+"	.endr\n"						\
 "	.equ	.L__gpr_num_zero,	0\n"			\
 "	.equ	.L__gpr_num_ra,		1\n"			\
 "	.equ	.L__gpr_num_sp,		2\n"			\