drm/v3d: Fix support for register debugging on the RPi 4

drm/v3d: Fix support for register debugging on the RPi 4

RPi 4 uses V3D 4.2, which is currently not supported by the register
definition stated at `v3d_core_reg_defs`. We should be able to support
V3D 4.2, therefore, change the maximum version of the register
definition to 42, not 41.

Fixes: 0ad5bc1ce463 ("drm/v3d: fix up register addresses for V3D 7.x")
Signed-off-by: Maíra Canal <mcanal@igalia.com>
Reviewed-by: Iago Toral Quiroga <itoral@igalia.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240109113126.929446-1-mcanal@igalia.com