NTB: epf: Allow more flexibility in the memory BAR map method

Support the below BAR configuration methods for epf NTB.

BAR 0: config and scratchpad
BAR 2: doorbell
BAR 4: memory map windows

Set difference BAR number information into struct ntb_epf_data. So difference
VID/PID can choose different BAR configurations. There are difference
BAR map method between epf NTB and epf vNTB Endpoint function.

Signed-off-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>