FMC: Staticize local symbols

This local symbol is used only in this file.
Fix the following sparse warnings:

drivers/fmc/fmc-write-eeprom.c:106:5: warning: symbol 'fwe_probe' was not declared. Should it be static?
drivers/fmc/fmc-write-eeprom.c:147:5: warning: symbol 'fwe_remove' was not declared. Should it be static?

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Acked-by: Alessandro Rubini <rubini@gnudd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>