soc/amd/stoneyridge: Fix and clean lpc.c

Rename set_lpc_resource to set_child_resource. Fix EC child resource not
recognized as already set. Remove code that's not needed.

BUG=b:62200877

Change-Id: I6e2bf9f8214b5f660084ccd622e3fe2c0cba7656
Signed-off-by: Richard Spiegel <richard.spiegel@silverbackltd.com>
Reviewed-on: https://review.coreboot.org/22093
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Marc Jones <marc@marcjonesconsulting.com>
1 file changed