kernel.bbclass: Remove bashism
Fixes build on systems using dash for default shell e.g.
errors like
run.do_strip.25842: [[: not found
| readelf: Error: Unable to read in 0x37 bytes of section headers
| readelf: Error: Not an ELF file - it has the wrong magic bytes at the start
Change-Id: I29cac15be44a02d75a3d6889b6ae9b2e19bf46af
(From OE-Core rev:
6956ffdc6e9879e32360b6ee3a3d286618807485)
Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Armin Kuster <akuster808@gmail.com>
