fix: handle EINTR correctly in get_cpu_mask_from_sysfs

fix: handle EINTR correctly in get_cpu_mask_from_sysfs

If the read() in get_cpu_mask_from_sysfs() fails with EINTR, the code is
supposed to retry, but the while loop condition has (bytes_read > 0),
which is false when read() fails with EINTR. The result is that the code
exits the loop, having only read part of the string.

Use (bytes_read != 0) in the while loop condition instead, since the
(bytes_read < 0) case is already handled in the loop.

Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I565030d4625ae199cabc4c2ab5eb8ac49ea4dfcb