cxgb4: update set_flash to flash different images

Chelsio adapter contains different flash regions and each
region is used by different binary files. This patch adds
support to flash images like PHY firmware, boot and boot config
using ethtool -f N.

The N value mapping is as follows.
N = 0 : Parse image and decide which region to flash
N = 1 : Firmware
N = 2 : PHY firmware
N = 3 : boot image
N = 4 : boot cfg

Signed-off-by: Vishal Kulkarni <vishal@chelsio.com&gt;">
Signed-off-by: David S. Miller <davem@davemloft.net>