Minor fixes for META/kernel_version.txt

- extractKernelVersionAndConfigs returns (version,config) but was
  incorrectly assigned to (config,version)
- kernel_version.txt generated by make has a newline at the end. This CL
  adds the newline to Soong's kernel_version.txt for bit-identical.

Test: Diff'd make and soong built kernel_version.txt
Change-Id: I3131d1253057715e0c361c8036769223e5965b7b