staging: rtl8712: fix camelcase in UserPriority

Replace camelcase variable UserPriority with snake case
variable user_priority.

Signed-off-by: Asif Khan <asif.kgauri@gmail.com>
Link: https://lore.kernel.org/r/20220904192400.8309-1-asif.kgauri@gmail.com


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