test: dm: Add a test for PCI Enhanced Allocation

This test is built on top of the existing swap_case driver.  It adds EA
capability structure support to swap_case and uses that to map BARs.
BAR1 works as it used to, swapping upper/lower case.  BARs 2,4 map to a
couple of magic values.

Signed-off-by: Alex Marginean <alexm.osslist@gmail.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>