phiopt: Use gimple_phi_result rather than PHI_RESULT [PR116643]

This converts the uses of PHI_RESULT in phiopt to be gimple_phi_result
instead. Since there was already a mismatch of uses here, it
would be good to use prefered one (gimple_phi_result) instead.

Bootstrapped and tested on x86_64-linux-gnu.

	PR tree-optimization/116643
gcc/ChangeLog:

	* tree-ssa-phiopt.cc (replace_phi_edge_with_variable): s/PHI_RESULT/gimple_phi_result/.
	(factor_out_conditional_operation): Likewise.
	(minmax_replacement): Likewise.
	(spaceship_replacement): Likewise.
	(cond_store_replacement): Likewise.
	(cond_if_else_store_replacement_1): Likewise.

Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com>