ARM: pxa/hx4700: Reduce sleep mode battery discharge by 35%

Drive the two Bluetooth UART output GPIOs (GPIO43_BTUART_TXD, GPIO45_BTUART_RTS)
LOW during sleep mode instead of HIGH. This reduces sleep mode battery discharge
from approximately 46 mA to approximately 30 mA.

Signed-off-by: Oliver Winker <oliver@oli1170.net>
Signed-off-by: Paul Parsons <lost.distance@yahoo.com>
Signed-off-by: Haojian Zhuang <haojian.zhuang@gmail.com>