kconfig: common: Fix memtest bool name

Fix the name appearing in menuconfig for memtest command

Signed-off-by: Nikolaos Pasaloukos <Nikolaos.Pasaloukos@imgtec.com>
Cc: Masahiro Yamada <yamada.m@jp.panasonic.com

common/Kconfig

@@ -133,7 +133,7 @@ config LOOPW
 	  Infinite write loop on address range
 
 config CMD_MEMTEST
-	bool "crc32"
+	bool "memtest"
 	help
 	  Simple RAM read/write test.