db845c: Switch default TARGET_KERNEL_USE to 5.4

It was requested that the default kernel be 5.4
based for db845c builds, so lets switch this.

Change-Id: I4ba0ce9916e63457a114d51cbe28ec7f830a1e2c
Signed-off-by: John Stultz <john.stultz@linaro.org>
1 file changed