interconnect: qcom: smd-rpm: drop duplicated QCOM_RPM_SMD_KEY_RATE define

The 'linux/soc/qcom/smd-rpm.h' header defines QCOM_RPM_SMD_KEY_RATE
with the exact same value.

$ git grep -nHE 'define[[:blank:]]+QCOM_RPM_SMD_KEY_RATE[[:blank:]]'
drivers/interconnect/qcom/smd-rpm.c:17:#define QCOM_RPM_SMD_KEY_RATE 0x007a484b
include/linux/soc/qcom/smd-rpm.h:52:#define QCOM_RPM_SMD_KEY_RATE 0x007a484b

Drop the local define to avoid the duplication.

No functional changes intended. Compile tested only.

Signed-off-by: Gabor Juhos <j4g8y7@gmail.com>
Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Link: https://lore.kernel.org/r/20260122-icc-qcom-dupe-defines-v1-1-eea876c2d98f@gmail.com
Signed-off-by: Georgi Djakov <djakov@kernel.org>