Relax ADDR_SPACE_GENERIC_P checks for default address space hooks

Relax ADDR_SPACE_GENERIC_P checks for default address space hooks

If all address spaces use the same modes and forms, we would
be forced to replicate these hooks in the backend.  Which would
then require the creation of a new hook to replace
target_default_pointer_address_modes_p.

	* targhooks.c (default_addr_space_pointer_mode): Remove check
	for generic address space.
	(default_addr_space_address_mode): Likewise.
	(default_addr_space_valid_pointer_mode): Likewise.
	(default_addr_space_legitimate_address_p): Likewise.
	(default_addr_space_legitimize_address): Likewise.

From-SVN: r229143