bpf: Reset register ID for BPF_END value tracking

In the Linux kernel, the following vulnerability has been resolved:

bpf: Reset register ID for BPF_END value tracking

When a register undergoes a BPF_END (byte swap) operation, its scalar

value is mutated in-place. If this register previously shared a scalar ID

with another register (e.g., after an `r1 = r0` assignment), this tie must

be broken.

Currently, the verifier misses resetting `dst_reg->id` to 0 for BPF_END.

Consequently, if a conditional jump checks the swapped register, the

verifier incorrectly propagates the learned bounds to the linked register,

leading to false confidence in the linked register's value and potentially

allowing out-of-bounds memory accesses.

Fix this by explicitly resetting `dst_reg->id` to 0 in the BPF_END case

to break the scalar tie, similar to how BPF_NEG handles it via

`__mark_reg_known`.