Staging: rtl8192e: Rename variable SlotNum

Rename variable SlotNum to slot_num to fix checkpatch warning Avoid
CamelCase.

Signed-off-by: Tree Davies <tdavies@darkphysics.net>
Link: https://lore.kernel.org/r/20240106055556.430948-14-tdavies@darkphysics.net


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