usb: ehci-s5p: fix: Fix null pointer dereferencing

usb: ehci-s5p: fix: Fix null pointer dereferencing

ab2c3b4: (USB: EHCI: make ehci-s5p a separate driver)
raised an issue with ehci-s5p's driver data.
Now that 's5p_ehci_hcd' doesn't maintain pointer to 'usb_hcd'
and s5p_ehci is nothing but a pointer to hcd->priv;
add hcd to the driver data rather than s5p_ehci.

This fixes issues with null pointer dereferencing in
s5p_ehci_shutdown(), s5p_ehci_suspend(), s5p_ehci_resume().

Signed-off-by: Vivek Gautam <gautam.vivek@samsung.com>
CC: Manjunath Goudar <manjunath.goudar@linaro.org>
CC: Arnd Bergmann <arnd@arndb.de>
CC: Jingoo Han <jg1.han@samsung.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>