ARM: pxa/cm-x300: properly set bt_reset pin

Fix below build warning and properly set bt_reset pin.

  CC      arch/arm/mach-pxa/cm-x300.o
arch/arm/mach-pxa/cm-x300.c: In function 'cm_x300_init_wi2wi':
arch/arm/mach-pxa/cm-x300.c:779: warning: unused variable 'wlan_en'
arch/arm/mach-pxa/cm-x300.c:795: warning: 'bt_reset' may be used uninitialized in this function

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Cc: <stable@kernel.org>
Acked-by: Igor Grinberg <grinberg@compulab.co.il>
Signed-off-by: Eric Miao <eric.y.miao@gmail.com>