lib: packing: replace bit_reverse() with bitrev8()

Remove bit_reverse() function.  Instead use bitrev8() from linux/bitrev.h +
bitshift.  Reduces code-repetition.

Signed-off-by: Uladzislau Koshchanka <koshchanka@gmail.com>
Link: https://lore.kernel.org/r/20221210004423.32332-1-koshchanka@gmail.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>