ios: Fix MSVC compiler warning

Fix warnings about const argument in virtual method signature:

src\plugins\ios\iosrunfactories.h:70:
warning: C4373: 'Ios::Internal::IosRunConfigurationFactory::doCreate':
virtual function overrides
'ProjectExplorer::IRunConfigurationFactory::doCreate', previous versions
of the compiler did not override when parameters only differed by
const/volatile qualifiers

This apparently was missed in 93304df0381c

Change-Id: I3402b6b4899d963dc8270e959de0e8dcbb0c15b1
Reviewed-by: hjk <hjk121@nokiamail.com>
Reviewed-by: Christian Kandeler <christian.kandeler@digia.com>