drm/panthor: Drop the dev_enter/exit() sections in _irq_suspend/resume()

There's no reason for _irq_suspend/resume() to be called after the
device has been unplugged, and keeping this dev_enter/exit()
section in _irq_suspend() is turns _irq_suspend() into a NOP
when called from the _unplug() functions, which we don't want.

v3:
- New patch

Fixes: 5fe909ca ("drm/panthor: Add the device logical block")
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240326111205.510019-3-boris.brezillon@collabora.com