staging: r8188eu: remove os_dep/xmit_linux.c

Move the last remaining function rtw_xmit_entry(), and the static
functions it calls, from os_dep/xmit_linux.c to core/rtw_xmit.c and
remove the now empty file os_dep/xmit_linux.c.

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/20220820181623.12497-19-straube.linux@gmail.com


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