Use devm_bitmap_zalloc() instead of hand-writing it.
It is less verbose and it improves the semantic.

While at it, use bitmap_zero() instead of hand-writing it.
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/fbde85a5e8ae99b10a2115d8ea1e69320a62947f.1657084786.git.christophe.jaillet@wanadoo.frSigned-off-by: Will Deacon <will@kernel.org>