Fix gcc 4.9 build issue in 5.10.y

Some older systems still compile kernels with old gcc version.
These warnings and errors show up when compiling with gcc 4.9.2

 error: "__GCC4_has_attribute___uninitialized__" is not defined [-Werror=undef]

Upstream won't need this because newer kernels are not compilable with gcc 4.9.

Subject: gcc-4.9 warning/error fix for 5.10.223-rc1
Fixes: fd7eea27 ("Compiler Attributes: Add __uninitialized macro")
Signed-off-by: Jari Ruusu <jariruusu@protonmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>