infiniband: fix core/fmr_pool.c kernel-doc notation

Fix kernel-doc warning for ib_fmr_pool_map_phys() and also format it
with function description and text spacing.

../drivers/infiniband/core/fmr_pool.c:404: warning: Excess function parameter 'pool' description in 'ib_fmr_pool_map_phys'

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Doug Ledford <dledford@redhat.com>
Cc: Jason Gunthorpe <jgg@mellanox.com>
Cc: linux-doc@vger.kernel.org
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>