i965: use strtol to convert the integer deviceID override

i965: use strtol to convert the integer deviceID override

One can override the deviceID, by setting the INTEL_DEVID_OVERRIDE
variable. A few symbolic names or a numerical value for the actual
device ID is accepted.

At the same time we're using strtod (string to double) to convert the
string to a decimal numeral. A seeming thinko, made by the original
commit that introduces the code in libdrm_intel and got here with the
import.

Fixes: 514db96c117a ("i965: Import libdrm_intel.")
Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
Reviewed-by: Eric Engestrom <eric.engestrom@imgtec.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>