IB/hfi1: Use bitmap_zalloc() when applicable

[ Upstream commit f86dbc9f ]

Use 'bitmap_zalloc()' to simplify code, improve the semantic and avoid
some open-coded arithmetic in allocator arguments.

Also change the corresponding 'kfree()' into 'bitmap_free()' to keep
consistency.

Link: https://lore.kernel.org/r/d46c6bc1869b8869244fa71943d2cad4104b3668.1637869925.git.christophe.jaillet@wanadoo.fr


Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Stable-dep-of: c9358de1 ("IB/hfi1: Fix wrong mmu_node used for user SDMA packet after invalidate")
Signed-off-by: Sasha Levin <sashal@kernel.org>