libcxgb: fix incorrect ppmax calculation

[ Upstream commit cc5a726c79158bd307150e8d4176ec79b52001ea ]

BITS_TO_LONGS() uses DIV_ROUND_UP() because of
this ppmax value can be greater than available
per cpu page pods.

This patch removes BITS_TO_LONGS() to fix this
issue.

Signed-off-by: Varun Prakash <varun@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>