usb: gadget: pxa25x_udc: use devm_ functions

This patch introduces the use of devm_request_irq, devm_gpio_request,
devm_clk_get etc. instead of the corresponding unmanaged interfaces. The
calls to the functions like free_irq to free the allocated resources are
removed as they are no longer required. Some labels in the probe function
are also done away with and the name of the label err_gpio_pullup is
changed to make it less specific to the context.

Signed-off-by: Himangi Saraogi <himangi774@gmail.com>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Felipe Balbi <balbi@ti.com>