'libgomp.c/usm-{1,2,3,4}.c': Re-enable non-GCN offloading compilation

'libgomp.c/usm-{1,2,3,4}.c': Re-enable non-GCN offloading compilation

Change '-foffload=amdgcn-amdhsa=[...]' to
'-foffload-options=amdgcn-amdhsa=[...]', so that non-GCN offloading compilation
doesn't get disabled.

Fix-up for og12 commit 6ec2c29dbbc19e7d2a8f991a5848e10c65c7c74c
"amdgcn, libgomp: USM allocation update".

	libgomp/
	* testsuite/libgomp.c/usm-1.c: Re-enable non-GCN offloading
	compilation.
	* testsuite/libgomp.c/usm-2.c: Likewise.
	* testsuite/libgomp.c/usm-3.c: Likewise.
	* testsuite/libgomp.c/usm-4.c: Likewise.