board/atmel: use correct sam-ba binary in flasher.sh script

board/atmel: use correct sam-ba binary in flasher.sh script

Instead of using the install of sam-ba under host/opt directly, use the symlink
created in host/bin.  The side effect of doing this instead allows the correct
sam-ba binary to be used based on the host arch being 32 bit or 64 bit.

Signed-off-by: Joshua Henderson <joshua.henderson@microchip.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
(cherry picked from commit e1452fe8434c4613d1727034db525c0a9bbc6dfd)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>