bitstream: fix hash file

bitstream: fix hash file

In commit d52e17701d73749fe81495b7c956268362ca0bbd
("package/bitstream: bump version to 1.4"), the hash file of the
bitstream package was not properly updated, with the md5 line being
wrong. This commit fixes this problem, which was noticed by
check-package:

package/bitstream/bitstream.hash:2: expected three fields (http://nightly.buildroot.org/#adding-packages-hash)
package/bitstream/bitstream.hash:2: hash size does not match type (http://nightly.buildroot.org/#adding-packages-hash)

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>