misc: use scandir with alphasort instead of readdir for consistency

During the image generation, When using the e2fsdroid with src_dir,
then dir files are listed with readdir, which will not guarantee
the order across the machines/fielsystems. So instead using the
scandir with alphasort option to list the files in sorted order.

Reported-by: Yasuhiro Kubota <yasuhiro.1.kubota@sony.com>
Signed-off-by: Vikram Dattu Thota <vikram.dattu@sony.com>
Signed-off-by: Takuya Ogawa <takuya.ogawa@sony.com>
Signed-off-by: Yoshitaka Seto <yoshitaka.seto@sony.com>
Tested-by: Yasuhiro Kubota <yasuhiro.1.kubota@sony.com>

Bug: 122874817

Change-Id: I4b946c737319252b82c74a0e10360843503862a1
1 file changed