timer: orion-timer: Add timer_get_boot_us() for BOOTSTAGE support

Add timer_get_boot_us() to support boards, that have CONFIG_BOOTSTAGE
enabled, like pogo_v4.

Signed-off-by: Stefan Roese <sr@denx.de>
Tested-by: Tony Dinh <mibodhi@gmail.com>
1 file changed