libxl: use LOGE instead of LIBXL__LOG_ERRNO in libxl_utils.c

libxl: use LOGE instead of LIBXL__LOG_ERRNO in libxl_utils.c

Code cleanup - no functional changes

The convenience macro LOGE has been written to take the place of
LIBXL__LOG_ERRNO. LOGE depends on the existence of a local libgl__gc
*gc. Replace two invocations of LIBXL__LOG_ERRNO, which are in
functions that already have a libxl__gc *gc present, to invocations
of the new macro.

Suggested-by: Ian Campbell <Ian.Campbell@citrix.com>
Signed-off-by: Kelley Nielsen <kelleynnn@gmail.com>
Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>