Fix predicate involving $HNV_ACTIVATED_KERNEL_NAME

Barebox's hush shell behaves differently than POSIX shells. The old
predicate [ "$HNV_ACTIVATED_KERNEL_NAME" = kernel1 ] evaluates to true
if $HNV_ACTIVATED_KERNEL_NAME is not set.

Change-Id: I40cca1d8139f96db1f5e8c7a9154cd843c640f4d
1 file changed