MA-14916-10 fix fastboot reboot bootloader issue

MA-14916-10 fix fastboot reboot bootloader issue

In Android, the reboot bootloader flag is written to misc partition, in
the boot flow, u-boot will check that message to decide whether enter
fastboot mode or not. To be compatible with the common implemention,
keep the fastboot_set_reboot_flag there and redefine it to avoid the
error return value which block the reboot process.

Change-Id: Ifb55236d5a5daf3edd124d3ed01851ff6e916e1a
Signed-off-by: faqiang.zhu <faqiang.zhu@nxp.com>
(cherry picked from commit aa78cbe3d3148ab99ea039ede767e6d1152092b4)