drm/msm/dpu: remove IS_ERR_OR_NULL for dpu_hw_intr_init() error handling

Using IS_ERR_OR_NULL() together with PTR_ERR() is a typical mistake. If
the value is NULL, then the function will return 0 instead of a proper
return code. Replace IS_ERR_OR_NULL() with IS_ERR() in the
dpu_hw_intr_init() error check.

Reviewed-by: Jessica Zhang <quic_jesszhan@quicinc.com>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/570036/
Link: https://lore.kernel.org/r/20231201211845.1026967-3-dmitry.baryshkov@linaro.org