drm/xe: fixup xe_alloc_pf_queue

drm/xe: fixup xe_alloc_pf_queue

kzalloc expects number of bytes, therefore we should convert the number
of dw into bytes, otherwise we are likely just accessing beyond the
array causing all kinds of carnage. Also fixup the error handling while
we are here.

v2:
 - Prefer kcalloc (dim)

Fixes: 3338e4f90c14 ("drm/xe: Use topology to determine page fault queue size")
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Stuart Summers <stuart.summers@intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240821171917.417386-2-matthew.auld@intel.com