redhat/kernel.spec: fix attributes of symvers file

Symvers file in /boot is 644: -rw-r--r--. 1 root root 165404 Jun 19 04:18 symvers-6.10.0-0.rc3.32.fc41.x86_64.xz

but in SPEC it's 600, which makes rpm -V complain about different mode:

rpm -V kernel-core

.M....... g /boot/symvers-6.10.0-0.rc3.32.fc41.x86_64.xz

This is presumably since we changed it from symlink to a copy in: 5b058c1e ("spec: make sure posttrans script doesn't fail if /boot is non-POSIX")

Signed-off-by: Jan Stancek jstancek@redhat.com