staging: rtl8723bs: replace _RND4 with round_up()

Use round_up instead of inline _RND4.

Signed-off-by: Ross Schmidt <ross.schm.dev@gmail.com>
Link: https://lore.kernel.org/r/20201004011743.10750-2-ross.schm.dev@gmail.com


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