imx: ventana: Rework CONFIG_CMD_GSC code to not be included in SPL

The command can only be used from full U-Boot, so do not build it into
SPL.

Cc: Stefano Babic <sbabic@denx.de>
Cc: Fabio Estevam <fabio.estevam@nxp.com>
Cc: Tim Harvey <tharvey@gateworks.com>
Signed-off-by: Tom Rini <trini@konsulko.com>
Acked-by: Tim Harvey <tharvey@gateworks.com>
Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>

board/gateworks/gw_ventana/gsc.c

@@ -172,7 +172,7 @@ int gsc_boot_wd_disable(void)
 	return 1;
 }
 
-#ifdef CONFIG_CMD_GSC
+#if defined(CONFIG_CMD_GSC) && !defined(CONFIG_SPL_BUILD)
 static int do_gsc_sleep(cmd_tbl_t *cmdtp, int flag, int argc,
 			char * const argv[])
 {