ehci-fsl: add PPC_MPC837x to default y

This patch converts USB_EHCI_FSL config option into the verbose
bool, so we'll able to select it for other freescale processors
with built-in EHCI controller.

Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Cc: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>