staging: rtl8712: Replace constant 49152 with expression 48 * 1024

This way we don't need the comment stating that 49152 equals 48k.

Signed-off-by: Mauro Dreissig <mukadr@gmail.com>
Link: https://lore.kernel.org/r/20200705143552.9368-2-mukadr@gmail.com


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