soc: qcom: dcc: Fix unsigned comparison with less than zero

The return value from the call to kstrtouint_from_user() is int.
However, the return value is being assigned to
an unsigned int variable 'ret', so making 'ret' an int.

Eliminate the following warning:
./drivers/soc/qcom/dcc.c:815:5-8: WARNING: Unsigned expression compared with zero: ret < 0

Link: https://bugzilla.openanolis.cn/show_bug.cgi?id=3638


Fixes: 4cbe60cf ("soc: qcom: dcc: Add driver support for Data Capture and Compare unit(DCC)")
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230106011710.2827-1-yang.lee@linux.alibaba.com