usb: renesas_usbhs: fixup sparse errors for common.c

This patch fixup below sparse errors

CHECK   ${RENESAS_USB}/common.c
${RENESAS_USB}/common.c:313:17: error: incompatible types in conditional expression (different base types)
${RENESAS_USB}/common.c:322:17: error: incompatible types in conditional expression (different base types)
${RENESAS_USB}/common.c:384:17: error: incompatible types in conditional expression (different base types)
${RENESAS_USB}/common.c:524:9: error: incompatible types in conditional expression (different base types)
${RENESAS_USB}/common.c:545:9: error: incompatible types in conditional expression (different base types)
${RENESAS_USB}/common.c:574:9: error: incompatible types in conditional expression (different base types)
${RENESAS_USB}/common.c:606:9: error: incompatible types in conditional expression (different base types)
${RENESAS_USB}/mod_gadget.c:233:28: warning: symbol 'req_clear_feature' was not declared. Should it be static?
${RENESAS_USB}/mod_gadget.c:274:28: warning: symbol 'req_set_feature' was not declared. Should it be static?
${RENESAS_USB}/mod_gadget.c:375:28: warning: symbol 'req_get_status' was not declared. Should it be static?

[ balbi@ti.com : added three sparse fixes to mod_gadget.c ]

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>