ARM: use the same branch insn on all architectures

For the "fixloop" implementation in start.S a number of different
instructions was used.  Unify code so all architectures use "blo"
here because it is more robust in case of incorrect alignments.

Signed-off-by: Wolfgang Denk <wd@denx.de>
Cc: Albert ARIBAUD <albert.aribaud@free.fr>
Cc: Minkyu Kang <mk7.kang@samsung.com>
Cc: Sandeep Paulraj <s-paulraj@ti.com>
Cc: Prafulla Wadaskar <prafulla@marvell.com>
Cc: Stefano Babic <sbabic@denx.de>
Cc: Marek Vasut <marek.vasut@gmail.com>
Acked-by: Heiko Schocher <hs@denx.de>