staging: r8188eu: remove intf_start pointer

Remove the intf_start pointer that points to a media-specific start
function (pci, usb, sdio, ...). The r8188eu driver supports only usb.

We could call usb_intf_start directly instead of going through the
function pointer. usb_intf_start is just a call to rtl8188eu_inirp_init so
we can directly replace the intf_start pointer with rtl8188eu_inirp_init.

Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Tested-by: Philipp Hortmann <philipp.g.hortmann@gmail.com> # Edimax N150
Link: https://lore.kernel.org/r/20230206201800.139195-5-martin@kaiser.cx


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>