linux-yocto: make kernel configuration audit user visible
After a linux-yocto style kernel is configured, a kernel configuration
audit is executed to detect common errors or issues with the config.
This output used to be visible, but was made less obvious to not alarm
users unnecessarily (since some configuration issues are acceptable).
There are some classes of configuration issue that are worth being
visible, and that is specified configuration values that do not make the
final .config. These dropped options can result in any number of runtime
failures, so flagging them at build time makes sense.
The visibility of auditing is controlled by KCONF_AUDIT_LEVEL:
0: no reporting
1: report options that are specified, but not in the final config
2: report options that are not hardware related, but set by a BSP
The default level is 1, with level 2 and above being for BSP development
only.
If these conditions are detected, warnings will be generated as follows:
WARNING: [kernel config]: specified values did not make it into the
kernel's final configuration:
Value requested for CONFIG_SND_PCSP not in final ".config"
Requested value: "CONFIG_SND_PCSP=y"
Actual value set: ""
