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/cmd/Kconfig b/cmd/Kconfig
index cb21dab..d440675 100644
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -533,6 +533,15 @@
 	help
 	  Simple RAM read/write test.
 
+if CMD_MEMTEST
+
+config SYS_ALT_MEMTEST
+	bool "Alternative test"
+	help
+	  Use a more complete alternative memory test.
+
+endif
+
 config CMD_MX_CYCLIC
 	bool "mdc, mwc"
 	help