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/ls1088aqds_sdcard_ifc_defconfig b/configs/ls1088aqds_sdcard_ifc_defconfig
index 33fc23c..4a2252f 100644
--- a/configs/ls1088aqds_sdcard_ifc_defconfig
+++ b/configs/ls1088aqds_sdcard_ifc_defconfig
@@ -20,6 +20,7 @@
 CONFIG_SPL_I2C_SUPPORT=y
 CONFIG_SPL_MPC8XXX_INIT_DDR_SUPPORT=y
 CONFIG_HUSH_PARSER=y
+CONFIG_CMD_MEMTEST=y
 CONFIG_CMD_I2C=y
 CONFIG_CMD_MMC=y
 CONFIG_CMD_USB=y