ahci_platform: Drop support for imx53-ahci platform device type

Since the 3.13 release the ahci_imx driver has proper devicetree enabled
support for ahci on imx53 and that is used instead of the old board file
created imx53-ahci platform device.

Note this patch also complete drops the id-table, an id-table is not needed
for a single id platform driver, the name field in the driver struct suffices.

And the code already has an explicit "MODULE_ALIAS("platform:ahci");" so the
id-table is not needed for that either.

Cc: Marek Vasut <marex@denx.de>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>