usb: host: ohci-st: Remove set but not used variable 'ohci'

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

drivers/usb/host/ohci-st.c: In function st_ohci_platform_probe:
drivers/usb/host/ohci-st.c:135:19: warning: variable ohci set but not used [-Wunused-but-set-variable]

It's never used, so can be removed.

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Acked-by: Patrice Chotard <patrice.chotard@st.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>