igep00x0: move SPL routines into separate file

Avoid cluttering board file with CONFIG_SPL_BUILD ifdefs
by moving SPL related functions into separate file.

Signed-off-by: Ladislav Michl <ladis@linux-mips.org>
Tested-by: Pau Pajuelo <ppajuel@gmail.com>
Acked-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
diff --git a/board/isee/igep00x0/Makefile b/board/isee/igep00x0/Makefile
index 68b151c..74594da 100644
--- a/board/isee/igep00x0/Makefile
+++ b/board/isee/igep00x0/Makefile
@@ -5,4 +5,8 @@
 # SPDX-License-Identifier:	GPL-2.0+
 #
 
-obj-y	:= igep00x0.o
+ifdef CONFIG_SPL_BUILD
+obj-y	:= spl.o common.o
+else
+obj-y	:= igep00x0.o common.o
+endif