usb: renesas_usbhs: fix type of buf

Fix the type of buf in __usbhsg_recip_send_status to
be __le16 to avoid the following sparse warning:

drivers/usb/renesas_usbhs/mod_gadget.c:335:14: warning: incorrect type in assignment (different base types)
drivers/usb/renesas_usbhs/mod_gadget.c:335:14:    expected unsigned short
drivers/usb/renesas_usbhs/mod_gadget.c:335:14:    got restricted __le16 [usertype]

Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>