ASoC: Tegra I2S: Remove dependency on pdev->id

When devices are instantiated from device-tree, pdev->id is set to -1.
Rework the driver so it doesn't depend on the ID.

Tegra I2S instantiated from board files are configured with pdev
name "tegra-i2s" and ID 0 or 1. The driver core then names the
device "tegra-i2s.0" or "tegra-i2s.1". This is not changing.

When a device is instantiated from device-tree, it will have
pdev->name="" and pdev->id=-1. For this reason, the pdev->id value is
not something we can rely on.

This patch doesn't actually change any names though:

When a device is instantiated from device-tree, the overall device name
will be "${unit_address}.${node_name}". This causes issues such as
clk_get() failures due to lack of a device-name match. To solve that,
AUXDATA was invented, to force a specific device name, thus allowing
dev_name() to return the same as the non-device-tree case. Tegra
currently uses AUXDATA for the I2S controllers. Eventually, AUXDATA will
go away, most likely replaced by phandle-based references within the
device tree.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>