usb: udc: pxa: remove unused platform_data

None of the remaining boards put useful data into the platform_data
structures, so effectively this only works with DT based probing.

Remove all code that references this data, to stop using the legacy
gpiolib interfaces. The pxa27x version already supports gpio
descriptors, while the pxa25x version now does it the same way.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://patch.msgid.link/20260427143300.2887692-1-arnd@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>