arm: socfpga: Zap spl.h and ad-hoc related syms

Switch to the common spl.h file and zap the arch/spl.h . Since the arch/spl.h
contained various ad-hoc symbols, zap those symbols as well and rework the
board configuration a little so it doesn't depend on them.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Chin Liang See <clsee@altera.com>
Cc: Dinh Nguyen <dinguyen@altera.com>
Cc: Vince Bridgers <vbridger@altera.com>
Cc: Albert Aribaud <albert.u.boot@aribaud.net>
Acked-by: Pavel Machek <pavel@denx.de>
diff --git a/arch/arm/include/asm/spl.h b/arch/arm/include/asm/spl.h
index e5daf89..8acd7cd 100644
--- a/arch/arm/include/asm/spl.h
+++ b/arch/arm/include/asm/spl.h
@@ -7,7 +7,7 @@
 #ifndef	_ASM_SPL_H_
 #define	_ASM_SPL_H_
 
-#if defined(CONFIG_OMAP) || defined(CONFIG_SOCFPGA) \
+#if defined(CONFIG_OMAP) \
 	|| defined(CONFIG_EXYNOS4) || defined(CONFIG_EXYNOS5) \
 	|| defined(CONFIG_EXYNOS4210)
 /* Platform-specific defines */