staging: r8188eu: Remove tests of kernel version

staging: r8188eu: Remove tests of kernel version

In the GitHub repository from which this driver was derived, old kernels
had to be supported. Now that the driver is included in the kernel,
this code can be removed as well as all mention of version.h.

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Link: https://lore.kernel.org/r/20210729170930.23171-3-Larry.Finger@lwfinger.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>