arm: socfpga: scan: Clean up horrible macros

Clean up the horrible macros present in the scan_manager.h . Firstly,
the function scan_mgr_io_scan_chain_prg() is static, yet all the macros
are used only within it, thus there is no point in having them in the
header file. Moreover, the macros are just making the code much less
readable, so remove them instead.

Signed-off-by: Marek Vasut <marex@denx.de>
Acked-by: Dinh Nguyen <dinguyen@opensource.altera.com>