ARM: 6291/1: coresight: move struct tracectx inside etm driver

This is done so as to be able to make use of the coresight components'
registers in assembler code (like omap sleep code). Also, there shouldn't
be any users of this structure outside the etm driver.

Change-Id: I847b2c3999df806608a9f3d5355a07363fea50d8
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Alexander Shishkin <virtuoso@slind.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>