If there's no GuC firmware entry in the table and the user didn't pass
an override path, the error message is very cryptic: xe will simply try
to continue and then fail when submitting the default context:

	xe 0000:00:02.0: [drm:xe_pci_probe [xe]] XE_LUNARLAKE  64b0:0001 dgfx:0 gfx:Xe2_LPG (20.04) media:Xe2_LPM (20.00) display:no dma_m_s:46 tc:1 gscfi:0
	...
	xe: probe of 0000:00:02.0 failed with error -22

Add an explicit error message and bail out:

	xe 0000:00:02.0: [drm:xe_pci_probe [xe]] XE_LUNARLAKE  64b0:0001 dgfx:0 gfx:Xe2_LPG (20.04) media:Xe2_LPM (20.00) display:no dma_m_s:46 tc:1 gscfi:0
	xe 0000:00:02.0: [drm] *ERROR* No GuC firmware defined for platform
	xe 0000:00:02.0: [drm] *ERROR* GuC init failed with -2
	...
	xe: probe of 0000:00:02.0 failed with error -2
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Francois Dugast <francois.dugast@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240201224724.551130-3-lucas.demarchi@intel.com