nb/intel/gm45/gma: Centralize call to gm45_get_lvds_edid_str()

There is only a single place where we need the LVDS EDID string. Let's
call gm45_get_lvds_edid_str() right there. This simplifies the API and
helps to follow the execution flow.

The function is moved to avoid a forward declaration.

Change-Id: I86f3a88e6b661bcf60319edbe301e70304924727
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/75378
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-by: Felix Singer <service+coreboot-gerrit@felixsinger.de>
diff --git a/src/northbridge/intel/gm45/gm45.h b/src/northbridge/intel/gm45/gm45.h
index d30ebe3..d929533 100644
--- a/src/northbridge/intel/gm45/gm45.h
+++ b/src/northbridge/intel/gm45/gm45.h
@@ -444,13 +444,11 @@
 	int pwm_freq; /* In Hz */
 };
 int get_blc_values(const struct blc_pwm_t **entries);
-u16 get_blc_pwm_freq_value(const char *edid_ascii_string);
+u16 get_blc_pwm_freq_value(void);
 
 #include <device/device.h>
 #include <edid.h>
 
-const char *gm45_get_lvds_edid_str(void);
-
 struct acpi_rsdp;
 unsigned long northbridge_write_acpi_tables(const struct device *device, unsigned long start,
 						struct acpi_rsdp *rsdp);