southbridge/intel/lynxpoint: add hard_reset to postcar

This fixes the following failure on certain google/peppy configs:

    build/postcar/lib/reset.o: In function `__hard_reset':
    /home/pgeorgi/coreboot/src/lib/reset.c:24: undefined reference to `do_hard_reset'

Change-Id: I448a8702a30108f1fc82179a766cbdd209336df7
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Reviewed-on: https://review.coreboot.org/26986
Reviewed-by: Martin Roth <martinroth@google.com>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/southbridge/intel/lynxpoint/Makefile.inc

@@ -55,4 +55,6 @@ ramstage-y += lp_gpio.c
 smm-$(CONFIG_HAVE_SMI_HANDLER) += lp_gpio.c
 endif
 
+postcar-y += reset.c
+
 endif