[PR121007, LRA]: Fall back to reload of whole inner address in PR case and constrain...

[PR121007, LRA]: Fall back to reload of whole inner address in PR case and constrain iteration number of address reloads

gcc/ChangeLog:

	* lra-constraints.cc (process_address_1): When changing base reg
	on a reg of the base class, fall back to reload of whole inner address.
	(process_address): Constrain the iteration number.

gcc/testsuite/ChangeLog:

	* gcc.target/powerpc/pr121007.c: New.