soc/amd/cezanne,picasso,sabrina: factor out get_threads_per_core

This code is common to at least all Zen-based APUs (Picasso, Cezanne,
Sabrina) and is also useful outside of the SoC-specific dynamic ACPI
table generation code.

Signed-off-by: Felix Held <felix-coreboot@felixheld.de>
Change-Id: Ie96d4429fb6ed9223efed9b3c754e04052d7ca7c
Reviewed-on: https://review.coreboot.org/c/coreboot/+/61357
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Rob Barnes <robbarnes@google.com>
Reviewed-by: Chris Wang <chris.wang@amd.corp-partner.google.com>
Reviewed-by: Eric Peers <epeers@google.com>

src/soc/amd/picasso/acpi.c

@@ -316,9 +316,7 @@ void generate_cpu_entries(const struct device *device)
 		},
 	};
 
-	threads_per_core = ((cpuid_ebx(CPUID_EBX_CORE_ID) & CPUID_EBX_THREADS_MASK)
-			    >> CPUID_EBX_THREADS_SHIFT)
-			   + 1;
+	threads_per_core = get_threads_per_core();
 	pstate_count = get_pstate_info(pstate_values, pstate_xpss_values);
 	logical_cores = get_cpu_count();