drm/msm/dpu: make error messages at dpu_core_irq_register_callback() more sensible

There is little point in using %ps to print a value known to be NULL. On
the other hand it makes sense to print the callback symbol in the
'invalid IRQ' message. Correct those two error messages to make more
sense.

Fixes: 68931991 ("drm/msm/dpu: stop using raw IRQ indices in the kernel output")
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Marijn Suijten <marijn.suijten@somainline.org>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Patchwork: https://patchwork.freedesktop.org/patch/585565/
Link: https://lore.kernel.org/r/20240330-dpu-irq-messages-v1-1-9ce782ae35f9@linaro.org


Signed-off-by: Abhinav Kumar <quic_abhinavk@quicinc.com>