acpi_add_ssdt_pstates: Remove function.

Nowhere in database p_state_num is set. So this whole function ends up
being a noop. Moreover the offsets used by it are wrong with any
optimizing iasl. Remove it in preparation of move to per-device ACPI.

Change-Id: I1f1f9743565aa8f0b8fca472ad4cb6d7542fcecb
Signed-off-by: Vladimir Serbinenko <phcoder@gmail.com>
Reviewed-on: http://review.coreboot.org/7012
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Tested-by: build bot (Jenkins)

src/arch/x86/include/arch/acpi.h

@@ -573,9 +573,6 @@ void acpi_jump_to_wakeup(void *wakeup_addr);
 int __attribute__((weak)) acpi_get_sleep_type(void);
 #endif	/* IS_ENABLED(CONFIG_HAVE_ACPI_RESUME) */
 
-/* northbridge/amd/amdfam10/amdfam10_acpi.c */
-unsigned long acpi_add_ssdt_pstates(acpi_rsdp_t *rsdp, unsigned long current);
-
 /* cpu/intel/speedstep/acpi.c */
 void generate_cpu_entries(void);