beep: restore a dependency definition to the previous one on x86 target
Commit 9bcea2de2c causes a dependency
problem with some out-of-tree packages which expect "DEPENDS:=+kmod-pcspkr".
To fix this problem, this commit restores a dependency definition to
the previous one on x86 target.
Signed-off-by: Yanase Yuki <dev@zpc.sakura.ne.jp>