USB: musb: be careful with 64K+ transfer lengths, host side

Feeding 32-bit length cast down to 'u16' to min() to calculate the FIFO
count in musb_host_tx() risks sending a short packet prematurely for
transfer sizes over 64 KB.

Similarly, although data transfer size shouldn't exceed 65535 bytes for
the control endpoint, making musb_h_ep0_continue() more robust WRT URBs
with possibly oversized buffer will not hurt either...

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