arm: odroid: Inherit default value for bootdelay from distro_bootcmd.

arm: odroid: Inherit default value for bootdelay from distro_bootcmd.

The default value with distro_bootcmd is 2 seconds, which is
reasonably fast, and provides a consistent experience across platforms
supporting distro_bootcmd.

The current bootdelay value of 0 seconds is a bit challenging to
interrupt when desired.

Acked-by: Lukasz Majewski <lukma@denx.de>
Signed-off-by: Vagrant Cascadian <vagrant@debian.org>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>