board/ronetix/pm9263/pm9263.c: Fix GCC 4.6 warning

Fix:
pm9263.c: In function 'pm9263_lcd_hw_psram_init':
pm9263.c:167:20: warning: variable 'x' set but not used
[-Wunused-but-set-variable]

Signed-off-by: Anatolij Gustschin <agust@denx.de>