ARM: make memset and memcpy prompt message more clearly

The origin SPL_USE_ARCH_MEMSET/MEMCPY use same prompt message
as USE_ARCH_MEMSET/MEMCPY, which makes it's hard to distinguish
them in menuconfig interface. This patch gives them different
prompt messages for spl and none-spl config.

Signed-off-by: Andy Yan <andy.yan@rock-chips.com>
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 46183ae..3c3f5f7 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -253,7 +253,7 @@
 	  but may increase the binary size.
 
 config SPL_USE_ARCH_MEMCPY
-	bool "Use an assembly optimized implementation of memcpy"
+	bool "Use an assembly optimized implementation of memcpy for SPL"
 	default y if USE_ARCH_MEMCPY
 	depends on !ARM64
 	help
@@ -271,7 +271,7 @@
 	  but may increase the binary size.
 
 config SPL_USE_ARCH_MEMSET
-	bool "Use an assembly optimized implementation of memset"
+	bool "Use an assembly optimized implementation of memset for SPL"
 	default y if USE_ARCH_MEMSET
 	depends on !ARM64
 	help