rpm2cpio.sh: fix to handle newline character

rpm2cpio.sh: fix to handle newline character

This script is attempting to read binary data from an rpm file.
If any of the bytes it is attempt to read is the binary value 0xa
(i.e. a newline) then the script does not properly deal with this
special case. Due to the behavior of command substitution, instead of
fetching the value 0xa, the script makes an error and get the value 0
instead.

The fix and the following explantion was taken from this post...

https://unix.stackexchange.com/questions/10801/
how-to-use-bash-script-to-read-binary-file-content

Command substitution $(…) strips final newlines in the command output.
There's a fairly easy workaround.  Make sure the output ends in a
character other than a newline, then strip that one character.

Signed-off-by: Lori Hikichi <lori.hikichi@broadcom.com>
Signed-off-by: Scott Branden <scott.branden@broadcom.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>