ARM: mx3: pcm037: remove unused variable

CC      arch/arm/mach-mx3/mach-pcm037.o
  arch/arm/mach-mx3/mach-pcm037.c: In function 'mxc_board_init':
  arch/arm/mach-mx3/mach-pcm037.c:584: warning: unused variable 'tmp'

Signed-off-by: Daniel Mack <daniel@caiaq.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>