riscv: rename CPU_RISCV_32/64 to match architecture names ARCH_RV32I/64I

RISC-V defines the base integer instruction sets as RV32I and RV64I.
Rename CPU_RISCV_32 and CPU_RISCV_64 to ARCH_RV32I and ARCH_RV64I to
match this convention.

Signed-off-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Rick Chen <rick@andestech.com>
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 168ca3d..7c76b4d 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -20,20 +20,20 @@
 source "board/emulation/qemu-riscv/Kconfig"
 
 choice
-	prompt "CPU selection"
-	default CPU_RISCV_32
+	prompt "Base ISA"
+	default ARCH_RV32I
 
-config CPU_RISCV_32
-	bool "RISC-V 32-bit"
+config ARCH_RV32I
+	bool "RV32I"
 	select 32BIT
 	help
-	  Choose this option to build an U-Boot for RISCV32 architecture.
+	  Choose this option to target the RV32I base integer instruction set.
 
-config CPU_RISCV_64
-	bool "RISC-V 64-bit"
+config ARCH_RV64I
+	bool "RV64I"
 	select 64BIT
 	help
-	  Choose this option to build an U-Boot for RISCV64 architecture.
+	  Choose this option to target the RV64I base integer instruction set.
 
 endchoice