Before, the Cypress chip power is always turn on either from internal battery
or from usb host. In this regard, the internal battery energy was spend on the
inactive chip. Now power of the Cypress chip is enabled only on the external usb host.
Change-Id: Iae7cddd1237ea9ed93fee5404575cc01543cb00c
Reviewed-on: http://gerrit.rockbox.org/433
Reviewed-by: Marcin Bukat <marcin.bukat@gmail.com>