misc: vexpress: Fix sparse non static symbol warnings

Fixes the following sparse warnings:

drivers/misc/vexpress-syscfg.c:133:22: warning:
 symbol 'vexpress_syscfg_regmap_config' was not declared. Should it be static?
drivers/misc/vexpress-syscfg.c:279:5: warning:
 symbol 'vexpress_syscfg_probe' was not declared. Should it be static?

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>