qlcnic: Pre-allocate DMA buffer used for minidump collection

Pre-allocate the physically contiguous DMA buffer used for
minidump collection at driver load time, rather than at
run time, to minimize allocation failures. Driver will allocate
the buffer at load time if PEX DMA support capability is indicated
by the adapter.

Signed-off-by: Shahed Shaikh <shahed.shaikh@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>