treewide: Migrate CONFIG_SYS_ALT_MEMTEST to Kconfig

Migrate the CONFIG_SYS_ALT_MEMTEST option to Kconfig.

Signed-off-by: Mario Six <mario.six@gdsys.cc>
[trini: Re-run migration after also including CMD_MEMTEST]
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/mx7ulp_evk_defconfig b/configs/mx7ulp_evk_defconfig
index 57c5ebf..78d7e0f 100644
--- a/configs/mx7ulp_evk_defconfig
+++ b/configs/mx7ulp_evk_defconfig
@@ -6,6 +6,7 @@
 CONFIG_SYS_EXTRA_OPTIONS="IMX_CONFIG=board/freescale/mx7ulp_evk/imximage.cfg"
 CONFIG_HUSH_PARSER=y
 CONFIG_CMD_BOOTZ=y
+CONFIG_CMD_MEMTEST=y
 CONFIG_CMD_GPIO=y
 CONFIG_CMD_I2C=y
 CONFIG_CMD_MMC=y