staging: r8188eu: rename three functions

staging: r8188eu: rename three functions

Prefix the names of the following functions with the driver name. The
original names are bad for the global namespace. While at it, convert
is_IBSS_empty() to all lower case to follow kernel coding style.

is_client_associated_to_ap()
is_client_associated_to_ibss()
is_IBSS_empty()

Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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/20221110090927.17274-1-straube.linux@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>