gfs: Use fixed GL_GLOCK_MIN_HOLD time

gfs: Use fixed GL_GLOCK_MIN_HOLD time

GL_GLOCK_MIN_HOLD represents the minimum time (in jiffies) that a glock
should be held before being eligible for release.  It is currently
defined as 10, meaning that the duration depends on the timer interrupt
frequency (CONFIG_HZ).  Change that time to a constant 10ms independent
of CONFIG_HZ.  On CONFIG_HZ=1000 systems, the value remains the same.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>