staging: rtl8723au: rtl8723a_hal_init: Improve code readability

This patch improves code readability in the function
rtl8723a_cal_txdesc_chksum.  It improves the readability of the argument
of the function le16_to_cpu.

Signed-off-by: Johannes Postma <jgmpostma@gmail.com>
Acked-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>