PCI: imx6: Remove unused assignment to variable ret

Previously, the maximum link speed was set following an "fsl,max-link-speed"
property read, and should the read failed, then the PCIe generation was
manually set to PCIe Gen1 and thus limiting the link speed to 2.5 GT/s.

Code refactoring completed in the commit 39bc5006 ("PCI: dwc:
Centralize link gen setting") changed to the logic that was previously
used to limit the maximum link speed leaving behind an unused assignment
to a variable "ret".

Since the value returned from the of_property_read_u32() and stored in
the variable "ret" is never used in any meaningful way, and it's also
immediately reassigned in the code that follows, the assignment can be
removed.

Link: https://lore.kernel.org/r/20211003025439.84783-1-kw@linux.com


Signed-off-by: Krzysztof Wilczyński <kw@linux.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>