UPSTREAM: random: convert to ENTROPY_BITS for better code readability

Signed-off-by: Yangtao Li <tiny.windzz@gmail.com>
Link: https://lore.kernel.org/r/20190607182517.28266-2-tiny.windzz@gmail.com


Signed-off-by: Theodore Ts'o <tytso@mit.edu>
(cherry picked from commit 12faac30d157970fdbfa171bbeb1fb88350303b1)
Signed-off-by: Mark Salyzyn <salyzyn@google.com>
Bug: 148665638
Change-Id: If96c7d9b69618ec879f1de1565cff0ac057ffe84