x86: config: add CONFIG_MITIGATION_VMSCAPE=y

x86: config: add CONFIG_MITIGATION_VMSCAPE=y

Introduced in the 6.6.106 update, set this new mitigation option to
be enabled. See: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/diff/arch/x86/Kconfig?id=v6.6.106&id2=v6.6.105

Signed-off-by: John Audia <[email protected]>
(cherry picked from commit 221eaf1339429e2dd3fe7cffe307240f87c4e032)
Signed-off-by: Goetz Goerisch <[email protected]>
Link: https://github.com/openwrt/openwrt/pull/20036
Signed-off-by: Hauke Mehrtens <[email protected]>