accel/ivpu: Fix missed error message after VPU rename

Change "VPU" to "NPU" in ivpu_suspend() so it matches all other error
messages.

Signed-off-by: Jacek Lawrynowicz <jacek.lawrynowicz@linux.intel.com>
Reviewed-by: Jeffrey Hugo <quic_jhugo@quicinc.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240402104929.941186-8-jacek.lawrynowicz@linux.intel.com