pci: fix msix device list remove-code

In pci_remove_device we want to remove only one device from the list.
The current code truncates our device list and drops the tail, fix that
by just unchaining one element.

Signed-off-by: Henning Schild <henning.schild@siemens.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
make: introduce make target docs_clean

Introduce a make target to remove generated documentation.

Signed-off-by: Henning Schild <henning.schild@siemens.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
docs: add x86 doxygen module

Signed-off-by: Henning Schild <henning.schild@siemens.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
docs: x86 apic: add x86 apic doxygen submodule

Add a new doxygen submodule and convert existing documentation to
doxygen style.

Signed-off-by: Henning Schild <henning.schild@siemens.com>
[Jan: renamed module to "APIC"]
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>