NTB: MFV 1db97f25: Pull out platform detection logic

Pull out read of PPD and platform detection logic to new functions,
ntb_detect_xeon(), ntb_detect_soc(). No functional change -- mostly
this is just shuffling the code to more closely match the Linux driver.
Linux commit log:

To simplify some of the platform detection code. Move the platform
detection to a function to be called earlier.

Authored by: Dave Jiang
Obtained from: Linux (Dual BSD/GPL driver)
Sponsored by: EMC / Isilon Storage Division