soc/amd/picasso: factor out UPD-M configuration from romstage

Move the parts of romstage.c that populate the UPD-M data structure to
the newly created fsp_m_params.c file. Since
platform_fsp_memory_init_params_cb gets called from the FSP driver and
not directly from car_stage_entry the two code parts in romstage.c
weren't directly interacting. Since soc/romstage.h only contains the
mainboard_updm_update function prototype, rename it to soc/fsp.h. This
patch also removes a few unused includes.

Signed-off-by: Felix Held <felix-coreboot@felixheld.de>
Change-Id: I52c21f13520dbdfab37587d17b3a8a3b1a780f36
Reviewed-on: https://review.coreboot.org/c/coreboot/+/51834
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Raul Rangel <rrangel@chromium.org>

src/soc/amd/picasso/Makefile.inc

@@ -19,6 +19,7 @@ bootblock-y += uart.c
 bootblock-y += gpio.c
 bootblock-y += reset.c
 
+romstage-y += fsp_m_params.c
 romstage-y += i2c.c
 romstage-y += romstage.c
 romstage-y += gpio.c