infiniband: rename random32() to prandom_u32()

infiniband: rename random32() to prandom_u32()

Use preferable function name which implies using a pseudo-random
number generator.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Reviewed-by: Steve Wise <swise@opengridcomputing.com>
Cc: Roland Dreier <roland@kernel.org>
Cc: Sean Hefty <sean.hefty@intel.com>
Cc: Hal Rosenstock <hal.rosenstock@gmail.com>
Reviewed-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>