USB: ohci-spear: Remove set but not used variable 'ohci'

Fixes gcc '-Wunused-but-set-variable' warning:

drivers/usb/host/ohci-spear.c: In function spear_ohci_hcd_drv_probe:
drivers/usb/host/ohci-spear.c:38:19: warning: variable ohci set but not used [-Wunused-but-set-variable]

It is never used since commit 1cc6ac59 ("USB:
OHCI: make ohci-spear a separate driver")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>