common: Add CONFIG_SKIP_RELOCATE

Add a check for CONFIG_SKIP_RELOCATE in reserve_uboot to skip the
relocation of the U-Boot image.
CONFIG_SKIP_RELOCATE skips relocation of U-Boot to the end of RAM
allowing for systems that have extremely limited RAM to run U-Boot.

Signed-off-by: Jesse Taube <Mr.Bossman075@gmail.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Caleb Connolly <caleb.connolly@linaro.org>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
diff --git a/common/board_f.c b/common/board_f.c
index e4e17dd..bff465d 100644
--- a/common/board_f.c
+++ b/common/board_f.c
@@ -477,6 +477,13 @@
 
 static int reserve_uboot(void)
 {
+	/*
+	 * This should be the first place GD_FLG_SKIP_RELOC is read from.
+	 * Set GD_FLG_SKIP_RELOC flag if CONFIG_SKIP_RELOCATE is enabled.
+	 */
+	if (CONFIG_IS_ENABLED(SKIP_RELOCATE))
+		gd->flags |= GD_FLG_SKIP_RELOC;
+
 	if (!(gd->flags & GD_FLG_SKIP_RELOC)) {
 		/*
 		 * reserve memory for U-Boot code, data & bss