USB: musb: fix data toggle saving with shared FIFO

For some strange reason the host side musb_giveback() decides
that it's always got an IN transfer when the hardware endpoint
is using a shared FIFO.  This causes musb_save_toggle() to read
the toggle state from the RXCSR register instead of TXCSR, and
may also cause unneeded reloading of RX endpoint registers.

Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>