powerpc/eeh: Refactor EEH flag accessors
There are multiple global EEH flags. Almost each flag has its own
accessor, which doesn't make sense. The patch refactors EEH flag
accessors so that they look unified:
eeh_add_flag(): Add EEH flag
eeh_clear_flag(): Clear EEH flag
eeh_has_flag(): Check if one specific flag has been set
eeh_enabled(): Check if EEH functionality has been enabled
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>