usb/ohci-omap: remove unused variable

Commit c2e935a7 "USB: move transceiver from ehci_hcd and ohci_hcd to
hcd and rename it as phy" removed the last use of the "ohci" variable
in the usb_hcd_omap_remove function, but left the variable in place
unused.

Without this patch, building omap1_defconfig results in:

In file included from drivers/usb/host/ohci-hcd.c:1013:0:
drivers/usb/host/ohci-omap.c: In function 'usb_hcd_omap_remove':
drivers/usb/host/ohci-omap.c:406:19: warning: unused variable 'ohci' [-Wunused-variable]

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Richard Zhao <richard.zhao@freescale.com>