drm/xe/pf: Update success code of pf_validate_vf_config()

This function may return negative error codes on invalid or
incomplete VF configuration, but unlike other int functions,
it was returning 1 instead of 0 on success, which might be
little inconvinient if we would like to use it directly in
other functions.

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Reviewed-by: Michał Winiarski <michal.winiarski@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240919171528.1451-3-michal.wajdeczko@intel.com