staging:rtl8192u: Refactor struct BA_RECORD - Style

Remove the 'typedef' directive from the BA_RECORD structure, to clear
the checkpatch issue with defining new types.

Additionally rename the structure to lowercase to comply with the
coding style.

These changes are purely coding style changes which should have no
impact on runtime code execution.

Signed-off-by: John Whitmore <johnfwhitmore@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>