soc: qcom: socinfo: Add support for new field in revision 17

Add support for new field coming with socinfo structure under v17 to get
hardware platform's oem variant id. This is to enable OEMs to have minor
changes in the board, but to use the same platform subtype as the one
supported by Qualcomm. The new field is to be used in platform overlay
file. Default value is 0, reserved for Qualcomm platforms. Also, add
debugfs support to read this field for a device.

Signed-off-by: Naman Jain <quic_namajain@quicinc.com>
Reviewed-by: Mukesh Ojha <quic_mojha@quicinc.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230127041200.29094-1-quic_namajain@quicinc.com