Let lib_get_sysinfo() pass through the success of get_coreboot_info()

Let lib_get_sysinfo() pass through the success of get_coreboot_info()

The return status of get_coreboot_info() might be handy to a platform
driver calling lib_get_sysinfo() to test for the presence of coreboot.

Change-Id: I0176c93ee92c9dff733112026ee50f2ca797bdff
Signed-off-by: Philip Prindeville <philipp@redfish-solutions.com>
Reviewed-on: http://review.coreboot.org/503
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>