exynos/snow: partial clean-up of snow bootblock using build class

This removes some duplicate code from Snow's mainboard bootblock
by utilizing the bootblock build class.

Change-Id: I153247370a8c5127260082dcdca3ebdc5e104fb8
Signed-off-by: David Hendricks <dhendrix@chromium.org>
Reviewed-on: http://review.coreboot.org/2270
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

src/arch/armv7/lib/Makefile.inc

@@ -1,3 +1,5 @@
+bootblock-y += syslib.c
+
 romstage-y += cache_v7.c
 romstage-y += cache-cp15.c
 romstage-y += div0.c