kernel: Delete unused KERNEL_LOCALVERSION variable

kernel: Delete unused KERNEL_LOCALVERSION variable

This has been unused since:

  commit fb61dc1430f81ae2ee59766ffab8404fd79ff1b1
  Author: Richard Purdie <richard@openedhand.com>
  Date:   Mon Jan 8 21:05:18 2007 +0000

      kernel.bbclass: Drop KERNEL_RELEASE variable

      git-svn-id: https://svn.o-hand.com/repos/poky/trunk@1123 311d38ba-8fff-0310-9ca6-ca027cbcb966

Signed-off-by: Alex Kiernan <alexk@zuma.ai>
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>