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/T1024RDB_SDCARD_defconfig b/configs/T1024RDB_SDCARD_defconfig
index 587c74d..c3a8404 100644
--- a/configs/T1024RDB_SDCARD_defconfig
+++ b/configs/T1024RDB_SDCARD_defconfig
@@ -25,6 +25,7 @@
 CONFIG_CMD_IMLS=y
 CONFIG_CMD_GREPENV=y
 CONFIG_CMD_MEMTEST=y
+CONFIG_SYS_ALT_MEMTEST=y
 CONFIG_CMD_I2C=y
 CONFIG_CMD_MMC=y
 CONFIG_CMD_SF=y