s390/hypfs: Eliminate hypfs interval

Currently the binary hypfs interfaces provides new data only once within
an interval time of one second. This patch removes this restriction and
now new data is returned immediately on every read on a hypfs binary file.

This is done in order to allow more consistent snapshots for programs
that read multiple hypfs binary files.

Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>