[vcpkg-cmake-config] Fix parsing of NO_PREFIX_CORRECTION

[Osyotr]

Currently passing NO_PREFIX_CORRECTION into vcpkg_cmake_config_fixup does nothing, except when additional argument is passed (i.e. NO_PREFIX_CORRECTION dummy). This PR changes that so no additional argument is needed.

My usage:

# use "cmake/Qt5WebKit" to match other Qt ports
vcpkg_cmake_config_fixup(PACKAGE_NAME "cmake/Qt5WebKit" CONFIG_PATH "lib/cmake/Qt5WebKit" DO_NOT_DELETE_PARENT_CONFIG_PATH NO_PREFIX_CORRECTION)
vcpkg_cmake_config_fixup(PACKAGE_NAME "cmake/Qt5WebKitWidgets" CONFIG_PATH "lib/cmake/Qt5WebKitWidgets" DO_NOT_DELETE_PARENT_CONFIG_PATH NO_PREFIX_CORRECTION)
file(REMOVE_RECURSE "${CURRENT_PACKAGES_DIR}/lib/cmake" "${CURRENT_PACKAGES_DIR}/debug/lib/cmake")