haswell: Make `copy_spd` a weak function

Instead of using function pointers, we can use weak functions. So, drop
the pointer from `romstage_params`, leaving `pei_data` as the only
remaining member. This will be cleaned up in a follow-up commit.

Change-Id: I3b17d21ea7a650734119a5cab4892fcb158b589d
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/43105
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
diff --git a/src/mainboard/google/slippy/variants/falco/romstage.c b/src/mainboard/google/slippy/variants/falco/romstage.c
index 96fbbab..901c70e 100644
--- a/src/mainboard/google/slippy/variants/falco/romstage.c
+++ b/src/mainboard/google/slippy/variants/falco/romstage.c
@@ -13,7 +13,7 @@
 #include "../../variant.h"
 
 /* Copy SPD data for on-board memory */
-static void copy_spd(struct pei_data *peid)
+void copy_spd(struct pei_data *peid)
 {
 	const int gpio_vector[] = {13, 9, 47, -1};
 	int spd_index = get_gpios(gpio_vector);
@@ -84,6 +84,4 @@
 
 	memcpy(rp->pei_data->usb2_ports, usb2_ports, sizeof(usb2_ports));
 	memcpy(rp->pei_data->usb3_ports, usb3_ports, sizeof(usb3_ports));
-
-	rp->copy_spd = copy_spd;
 }