mmc: core: Scan the eMMC boot areas for partition table

mmc: core: Scan the eMMC boot areas for partition table

It appears that some vendors provision the boot areas with valid part
tables (GPT) in order to have identifiable partitions for device and
firmware specific data, such has the qualcomm CDT (Qualcomm Config
Data Table). Additionally, these boot areas can be utilized to host
device-specific IDs, calibration data, and other critical information.

Signed-off-by: Loic Poulain <loic.poulain@oss.qualcomm.com>
Link: https://lore.kernel.org/r/20250507134538.575912-1-loic.poulain@oss.qualcomm.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>