Revert "riscv: image: Add new image type for RV64"

This reverts commit 14a4792a71db3561bea065415ac1f2ac69ef32b5 as
discussed in [1].

[1] https://lists.denx.de/pipermail/u-boot/2025-May/590841.html

Signed-off-by: Mayuresh Chitale <mchitale@ventanamicro.com>
Reviewed-by: Leo Yu-Chi Liang <ycliang@andestech.com>
diff --git a/boot/image.c b/boot/image.c
index 45299a7..139c5bd 100644
--- a/boot/image.c
+++ b/boot/image.c
@@ -92,8 +92,7 @@
 	{	IH_ARCH_ARC,		"arc",		"ARC",		},
 	{	IH_ARCH_X86_64,		"x86_64",	"AMD x86_64",	},
 	{	IH_ARCH_XTENSA,		"xtensa",	"Xtensa",	},
-	{	IH_ARCH_RISCV,		"riscv",	"RISC-V 32 Bit",},
-	{	IH_ARCH_RISCV64,	"riscv64",	"RISC-V 64 Bit",},
+	{	IH_ARCH_RISCV,		"riscv",	"RISC-V",	},
 	{	-1,			"",		"",		},
 };