soc/qualcomm/sdm845: Fix broken Kconfig

This fixes the following changes, which made qualcomm Kconfig
appear on all platforms:

bd0b51c0be
7a3e46d767

Use proper Kconfig logic.

Change-Id: I0195fd186ac39dd4258fe0781dd6d3d1b1d1679f
Signed-off-by: Patrick Rudolph <siro@das-labor.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/32805
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-by: Julius Werner <jwerner@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/soc/qualcomm/common/Kconfig

@@ -1,5 +1,15 @@
 
+config SOC_QUALCOMM_COMMON
+	bool
+	default n
+	help
+	  Selected by platforms that use the common code.
+
+if SOC_QUALCOMM_COMMON
+
 config QC_SDI_ENABLE
 	bool
 	default n
 	prompt "Debug Build: enable SDI"
+
+endif

src/soc/qualcomm/sdm845/Kconfig

@@ -10,6 +10,7 @@ config SOC_QUALCOMM_SDM845
 	select GENERIC_UDELAY
 	select HAVE_MONOTONIC_TIMER
 	select ARM64_USE_ARCH_TIMER
+	select SOC_QUALCOMM_COMMON
 
 if SOC_QUALCOMM_SDM845