bnxt_en: Do not modify max IRQ count after RDMA driver requests/frees IRQs.

Calling bnxt_set_max_func_irqs() to modify the max IRQ count requested or
freed by the RDMA driver is flawed.  The max IRQ count is checked when
re-initializing the IRQ vectors and this can happen multiple times
during ifup or ethtool -L.  If the max IRQ is reduced and the RDMA
driver is operational, we may not initailize IRQs correctly.  This
problem shows up on VFs with very small number of MSIX.

There is no other logic that relies on the IRQ count excluding the ones
used by RDMA.  So we fix it by just removing the call to subtract or
add the IRQs used by RDMA.

Fixes: a588e458

 ("bnxt_en: Add interface to support RDMA driver.")
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>