select: rename estimate_accuracy to select_estimate_accuracy

select: rename estimate_accuracy to select_estimate_accuracy

Make it a subsystem-specific identifier because we wish to amke it
non-static in the next patch ("epoll: make epoll_wait() use the hrtimer
range feature").

Change-Id: I2b1654d51699b4c0753673228cec7e90485c9806
Cc: Shawn Bohrer <shawn.bohrer@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Davide Libenzi <davidel@xmailserver.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>