staging: r8188eu: merge rtw_os_recvbuf_resource_alloc() into rtw_recv.c

staging: r8188eu: merge rtw_os_recvbuf_resource_alloc() into rtw_recv.c

Merge the functionality of the function rtw_os_recvbuf_resource_alloc()
into rtl8188eu_init_recv_priv(). Merging the functionality instead of
just making the function static improves readability and we have one
function less to care about when converting the uses of _FAIL/_SUCCESS
to normal kernel error code logic.

Tested-by: Philipp Hortmann <philipp.g.hortmann@gmail.com> # Edimax N150
Signed-off-by: Michael Straube <straube.linux@gmail.com>
Link: https://lore.kernel.org/r/20220807181538.8499-3-straube.linux@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>