syscon: fix prototype compile error ...

gcc 4.8.3 throws the following error

include/mfd/syscon.h: In function 'syscon_base_lookup_by_pdevname':
include/mfd/syscon.h:22:1: error: parameter name omitted
 static inline void __iomem *syscon_base_lookup_by_pdevname(const char *)

Fix it by adding the name to the function prototype.

Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

mfd: syscon: Introduce syscon_base_lookup_by_phandle() function ...

Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Add system controller register driver (SYSCON) ...

This patch adds support for system controller register driver (SYSCON).
Code taken from Linux Kernel and adapted for using in barebox.

Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>