amd/microcode: Add API to obtain address on microcode update block

Expose API to return the microcode update block address. It will be
used to provide a pointer to microcode update to the OpenSIL.

Change-Id: I1a5a89a5ff2ed29621e856cf274434803005aff8
Signed-off-by: Michał Żygowski <michal.zygowski@3mdeb.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/89108
Reviewed-by: Alicja Michalska <ahplka19@gmail.com>
Reviewed-by: Matt DeVillier <matt.devillier@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/include/cpu/amd/microcode.h

@@ -7,5 +7,6 @@ void amd_update_microcode_from_cbfs(void);
 void amd_load_microcode_from_cbfs(void);
 void amd_free_microcode(void);
 void amd_apply_microcode_patch(void);
+void *amd_microcode_find(void);
 
 #endif /* CPU_AMD_MICROCODE_H */

src/soc/amd/common/block/cpu/update_microcode.c

@@ -119,3 +119,10 @@ void amd_free_microcode(void)
 		ucode = NULL;
 	}
 }
+
+void *amd_microcode_find(void)
+{
+	amd_load_microcode_from_cbfs();
+
+	return (void *)ucode;
+}