ASoC: fsl-asoc-card: set priv->pdev before using it

In the Linux kernel, the following vulnerability has been resolved:

ASoC: fsl-asoc-card: set priv->pdev before using it

priv->pdev pointer was set after being used in

fsl_asoc_card_audmux_init().

Move this assignment at the start of the probe function, so

sub-functions can correctly use pdev through priv.

fsl_asoc_card_audmux_init() dereferences priv->pdev to get access to the

dev struct, used with dev_err macros.

As priv is zero-initialised, there would be a NULL pointer dereference.

Note that if priv->dev is dereferenced before assignment but never used,

for example if there is no error to be printed, the driver won't crash

probably due to compiler optimisations.