fbcon: delay the start of the cursor timer until a con_switch()

As reported in Bugzilla Bug 9093, upon switching to X, a small rectangular
cursor can still be seen blinking in the upper left part of the screen.  It is
fbcon's text cursor.  This is caused by a strange ioctl(..., KDSETMODE,
KD_TEXT) call done by something in userspace, perhaps by X itself, while the
tty is still in graphics mode.  And when the tty is in KD_TEXT mode, the
cursor timer is restarted.

Although this is a userspace problem, we can work around it by delaying the
restart of the cursor timer until an fbcon_switch() is called.  In other
words, the cursor timer will not be restarted even if a KD_TEXT mode switch is
requested.

Regression potential: Present but low

Signed-off-by: Antonino Daplas <adaplas@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>