Preserve bridge MTU in KVM ifup script
Preserve bridge MTU in KVM ifup script

Closes: #201 - KVM_IFUP does not set bridge-MTU on tap devices
Signed-off-by: Andrea Spadaccini <92d490849ac1b40cd8e8878e4d94603bebdb089f@google.com>
Reviewed-by: Iustin Pop <acf83a5274f31a43af6b914614365999469c1a31@google.com>
Reviewed-by: Michael Hanselmann <68b67885ff74281219b4a4be33cc20fd45078d7c@google.com>

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