staging: unisys: visorbus: Remove unnecessary EXPORT_SYMBOL statements

The driver that is now visorbus started out as multiple separate drivers,
and when they were merged the EXPORT_SYMBOL statements that were required
for separate drivers were left in the code. This patch removes those now
unnecessary exports.

Signed-off-by: Bryan Thompson <bryan.thompson@unisys.com>
Signed-off-by: David Kershner <david.kershner@unisys.com>
Reviewed-by: Tim Sell <Timothy.Sell@unisys.com>
Acked-By: Neil Horman <nhorman@tuxdriver.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>