eal/bsd: fix read on PCI configuration space

eal/bsd: fix read on PCI configuration space

Some drivers (such as virtio) may need to read more than 4 bytes
data from PCI configuration space via rte_eal_pci_read_config().
But it will return with an error on FreeBSD when the expected
data length is bigger than the size of pi.pi_data whose type is
u_int32_t. This patch removes this limitation.

Fixes: 632b2d1deeed ("eal: provide functions to access PCI config")
Cc: stable@dpdk.org
Signed-off-by: Tiwei Bie <tiwei.bie@intel.com>
Acked-by: Bruce Richardson <bruce.richardson@intel.com>