ixgbe: reduce number of reads when getting OROM data

ixgbe: reduce number of reads when getting OROM data

Currently, during locating the CIVD section, the ixgbe driver loops
over the OROM area and at each iteration reads only OROM-datastruct-size
amount of data. This results in many small reads and is inefficient.

Optimize this by reading the entire OROM bank into memory once before
entering the loop. This significantly reduces the probing time.

Without this patch probing time may exceed over 25s, whereas with this
patch applied average time of probe is not greater than 5s.

without the patch:
[14:12:22] ixgbe: Copyright (c) 1999-2016 Intel Corporation.
[14:12:25] ixgbe 0000:21:00.0: Multiqueue Enabled: Rx Queue count = 63, Tx Queue count = 63 XDP Queue count = 0
[14:12:25] ixgbe 0000:21:00.0: 63.012 Gb/s available PCIe bandwidth (16.0 GT/s PCIe x4 link)
[14:12:26] ixgbe 0000:21:00.0: MAC: 7, PHY: 27, PBA No: N55484-001
[14:12:26] ixgbe 0000:21:00.0: 20:3a:43:09:3a:12
[14:12:26] ixgbe 0000:21:00.0: Intel(R) 10 Gigabit Network Connection
[14:12:50] ixgbe 0000:21:00.0 ens2f0np0: renamed from eth0

with the patch:
[14:18:18] ixgbe: Copyright (c) 1999-2016 Intel Corporation.
[14:18:19] ixgbe 0000:21:00.0: Multiqueue Enabled: Rx Queue count = 63, Tx Queue count = 63 XDP Queue count = 0
[14:18:19] ixgbe 0000:21:00.0: 63.012 Gb/s available PCIe bandwidth (16.0 GT/s PCIe x4 link)
[14:18:19] ixgbe 0000:21:00.0: MAC: 7, PHY: 27, PBA No: N55484-001
[14:18:19] ixgbe 0000:21:00.0: 20:3a:43:09:3a:12
[14:18:19] ixgbe 0000:21:00.0: Intel(R) 10 Gigabit Network Connection
[14:18:22] ixgbe 0000:21:00.0 ens2f0np0: renamed from eth0

Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Paul Menzel <pmenzel@molgen.mpg.de>
Signed-off-by: Jedrzej Jagielski <jedrzej.jagielski@intel.com>
Tested-by: Rinitha S <sx.rinitha@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>