externalsrc: fix support in various components
Affected components:
- cpupower
- intel-speed-select
- spidev-test
When the externalsrc class is used the tasks listed in SRCTREECOVEREDTASKS
are deleted to prevent them being executed. If externalsrc is used for
the kernel then this will include virtual/kernel:do_patch.
Signed-off-by: Andrej Valek <andrej.v@skyrain.eu>
Signed-off-by: Khem Raj <raj.khem@gmail.com>