package/keyutils: re-enable package on microblaze

package/keyutils: re-enable package on microblaze

keyutils has a !BR2_microblaze introduced by commit:
https://git.buildroot.net/buildroot/commit/?id=20e0926f4469a3486629cfd6fa7f449f2b659aa8
that points 2 possible build failures:
- "warning: dereferencing type-punned pointer will break strict-aliasing
  rules" treated as an error. But this warning is not treated as an
  error anymore since -Werror flag is not used after last version bumps
- glibc does not export the resolver symbols resulting in linking
  failure. But glibc used was version 2.3.6 that is not used anymore
  since. It's been released in 2005.

So re-enable package for Microblaze by removing 'depends on
!BR2_microblaze' from keyutils Config.in

Signed-off-by: Giulio Benetti <giulio.benetti@micronovasrl.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>