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_plugin_defconfig b/configs/mx7ulp_evk_plugin_defconfig
index ab782a0..f9057bb 100644
--- a/configs/mx7ulp_evk_plugin_defconfig
+++ b/configs/mx7ulp_evk_plugin_defconfig
@@ -5,6 +5,7 @@
 CONFIG_DEFAULT_DEVICE_TREE="imx7ulp-evk"
 CONFIG_SYS_EXTRA_OPTIONS="IMX_CONFIG=board/freescale/mx7ulp_evk/imximage.cfg"
 CONFIG_HUSH_PARSER=y
+CONFIG_CMD_MEMTEST=y
 CONFIG_CMD_GPIO=y
 CONFIG_CMD_I2C=y
 CONFIG_CMD_MMC=y