Currently the feature test for the SPE extension requires the feature
bits in the ID_AA64DFR0 register to read exactly 0b0001.
However the architecture guarantees that any values greater than 0
indicate the presence of a feature, which is what we are after in
our spe_supported() function.

Change the comparison to include all values greater than 0.

This fixes SPE support in non-secure world on implementations which
include the Scalable Vector Extension (SVE), for instance on Zeus cores.

Change-Id: If6cbd1b72d6abb8a303e2c0a7839d508f071cdbe
Signed-off-by: Andre Przywara <andre.przywara@arm.com>