habanalabs: skip valid test for boot_dev_sts regs

Get rid of the need to check if boot_dev_sts is valid on every access
to value read from these registers.

This is done by storing the register value in hdev props ONLY if
register is enabled.

This way if register is NOT enabled all capability bits will not be set.

Signed-off-by: Ohad Sharabi <osharabi@habana.ai>
Reviewed-by: Oded Gabbay <ogabbay@kernel.org>
Signed-off-by: Oded Gabbay <ogabbay@kernel.org>