digsig: allocate digsig_kobject on heap

Use kobject_create_and_add() to allocate digsig_kobject on the heap.
This patch also resolves a kernel panic on boot caused by trying to
initialize a seemingly already initialized kobject.

Signed-off-by: Rupert Muchembled <rupert@rmuch.net>
digsig: init module using module_init()

Initialize module with module_init() rather than security_initcall().

Although the module should be initialized with security_initcall() like
the rest of the kernel security modules, it seems we cannot call
digsig_init_sysfs() so early on in the kernel initialization without
causing a panic due to a null pointer dereference.

Eventually, the module should use securityfs for communication with
user space.

Signed-off-by: Rupert Muchembled <rupert@rmuch.net>
digsig: remove conditional for old kernel versions

There is no need to keep legacy support for a kernel released in June
2005, so we can safely remove this compatibility check.

Signed-off-by: Rupert Muchembled <rupert@rmuch.net>
digsig: remove git exec bit from dsi.h

Remove git exec bit from dsi.h.

Signed-off-by: Rupert Muchembled <rupert@rmuch.net>
digsig: remove documentation from source directory

Remove miscellaneous documentation files from the source directory.

Signed-off-by: Rupert Muchembled <rupert@rmuch.net>