[PATCH v3] soc: qcom: ubwc: Fix link error when QCOM_SMEM=n

DRM_MSM unconditionally selects QCOM_UBWC_CONFIG, which calls SMEM APIs,
causing a link error on non-Qcom platforms (e.g. SOC_IMX5):

  arm-linux-gnueabihf-ld: ubwc_config.c:(.text+0x2c): undefined
      reference to 'qcom_smem_is_available'
  arm-linux-gnueabihf-ld: ubwc_config.c:(.text+0x4c): undefined
      reference to 'qcom_smem_dram_get_hbb'

Make QCOM_UBWC_CONFIG depend on QCOM_SMEM to make the requirement
explicit, and guard the select in DRM_MSM with ARCH_QCOM && QCOM_SMEM so
it is only selected when its dependency is met.

Fixes: 1b445022d1d0 ("soc: qcom: ubwc: Get HBB from SMEM")
Signed-off-by: Daniel Baluta <[email protected]>
---
Changes since v2:
 - guard QCOM_UBWC_CONFIG both with ARCH_QCOM and QCOM_SMEM otherwise
we could force QCOM_SMEM=n and still have QCOM_UBWC_CONFIG=m as reported
by Nathan Chancellor
 - Link to v2: https://lore.kernel.org/imx/20260811223622.GA934543@ax162/T/#t

Changes since v1:
- (addressed feedback from Dmitry) replace adding static inline stubs with preparing a better config
  dependecies so that we use the qcom_smem symbols only on QCOM platforms.
- Link to v1: https://lore.kernel.org/imx/sy2ulk536ryakhy6fdnqr4asvzvufqk3dlo2awdrfomulyf4n4@qtp4qoazqmhj/T/#t

 drivers/gpu/drm/msm/Kconfig | 2 +-
 drivers/soc/qcom/Kconfig    | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/msm/Kconfig b/drivers/gpu/drm/msm/Kconfig
index 09469d56513b0..1670dbc9464c6 100644
--- a/drivers/gpu/drm/msm/Kconfig
+++ b/drivers/gpu/drm/msm/Kconfig
@@ -22,7 +22,7 @@ config DRM_MSM
 	select TMPFS
 	select QCOM_SCM
 	select QCOM_PAS
-	select QCOM_UBWC_CONFIG
+	select QCOM_UBWC_CONFIG if ARCH_QCOM && QCOM_SMEM
 	select WANT_DEV_COREDUMP
 	select SND_SOC_HDMI_CODEC if SND_SOC
 	select SYNC_FILE
diff --git a/drivers/soc/qcom/Kconfig b/drivers/soc/qcom/Kconfig
index fd4d4ecd2df0f..e0629e9328c87 100644
--- a/drivers/soc/qcom/Kconfig
+++ b/drivers/soc/qcom/Kconfig
@@ -321,6 +321,7 @@ config QCOM_QMI_HELPERS
 
 config QCOM_UBWC_CONFIG
 	tristate
+	depends on QCOM_SMEM
 	help
 	  Most Qualcomm SoCs feature a number of Universal Bandwidth Compression
 	  (UBWC) engines across various IP blocks, which need to be initialized
-- 
2.45.2