google/grunt: Move PSP_SELECTABLE_SMU_FW to soc

Now that an updated bootloader with important fixes is available at coreboot
repository, all stoneyridge boards should use it. Move the selection of
SOC_AMD_PSP_SELECTABLE_SMU_FW from mb/google/kahlee to soc/amd/stoneyridge.

BUG=b:111428800
TEST=Build and boot grunt.

Change-Id: Idf8e348efbc85569aa1163125f412c5242c46eb4
Signed-off-by: Richard Spiegel <richard.spiegel@silverbackltd.com>
Reviewed-on: https://review.coreboot.org/27844
Reviewed-by: Martin Roth <martinroth@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/google/kahlee/Kconfig

@@ -30,7 +30,6 @@ config BOARD_GOOGLE_BASEBOARD_KAHLEE
 	select MAINBOARD_HAS_CHROMEOS
 	select SERIRQ_CONTINUOUS_MODE
 	select STONEYRIDGE_UART
-	select SOC_AMD_PSP_SELECTABLE_SMU_FW
 	select SOC_AMD_SMU_FANLESS
 	select HAVE_ACPI_RESUME
 	select DRIVERS_GENERIC_BH720

src/soc/amd/stoneyridge/Kconfig

@@ -66,6 +66,7 @@ config CPU_SPECIFIC_OPTIONS
 	select SSE
 	select SSE2
 	select RTC
+	select SOC_AMD_PSP_SELECTABLE_SMU_FW
 
 config VBOOT
 	select VBOOT_SEPARATE_VERSTAGE