Revise iovec_t.__eq__ and vfu_dma_info_t.__eq__ to fix flake8 E721

The newer flake8 version in the arch linux job of the pull request
workflow fails due to:

E721 do not compare types, for exact checks use `is` / `is not`, for instance checks use `isinstance()`

Both `__eq__` functions now use `is not` instead of `!=` for the type
initial check.

Signed-off-by: Sandro-Alessio Gierens <sandro@gierens.de>
diff --git a/test/py/libvfio_user.py b/test/py/libvfio_user.py
index 6d60798..f29b50e 100644
--- a/test/py/libvfio_user.py
+++ b/test/py/libvfio_user.py
@@ -315,7 +315,7 @@
     ]
 
     def __eq__(self, other):
-        if type(self) != type(other):
+        if type(self) is not type(other):
             return False
         return self.iov_base == other.iov_base \
             and self.iov_len == other.iov_len
@@ -491,7 +491,7 @@
     ]
 
     def __eq__(self, other):
-        if type(self) != type(other):
+        if type(self) is not type(other):
             return False
         return self.iova == other.iova \
             and self.vaddr == other.vaddr \