ARM: dts: everest: Define name for gpio line B6

gpio-line-names B6 set to checkstop

Signed-off-by: Ben Tyner <ben.tyner@ibm.com>
Reviewed-by: Eddie James <eajames@linux.ibm.com>
Link: https://lore.kernel.org/r/20210920150549.6431-4-bentyner@linux.ibm.com


Signed-off-by: Joel Stanley <joel@jms.id.au>