USB: oxu210hp-hcd.c: use devm_ functions

This patch introduces the use of devm_ioremap_resource instead of
request_mem_region and ioremap. The error handling on
platform_get_resource and the error message for ioremap are removed. The
function devm_kzalloc replaces memory allocation by unmanaged kzalloc. The
function calls to free the allocated memory in the probe and remove
functions are done away with. Some labels are removed and a label error
is added to make is less specific to the context. The debug message is
removed as devm_ioremap generates debug messages of its own.

Signed-off-by: Himangi Saraogi <himangi774@gmail.com>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>