PXA: Fix warning in zipitz2

Configuring for zipitz2 board...
zipitz2.c: In function ‘board_mmc_init’:
zipitz2.c:85:2: warning: implicit declaration of function ‘pxa_mmc_register’ [-Wimplicit-function-declaration]

Signed-off-by: Marek Vasut <marek.vasut@gmail.com>
1 file changed