dell-smbios: rename dell_smi_error() to dell_smbios_error()

As dell_smi_error() is exported by dell-smbios, its prefix should be
consistent with other exported symbols, so change function name to
dell_smbios_error().

Signed-off-by: Michał Kępień <kernel@kempniu.pl>
Reviewed-by: Pali Rohár <pali.rohar@gmail.com>
Signed-off-by: Darren Hart <dvhart@linux.intel.com>