clk: qcom: common: fix legacy board-clock registration

[ Upstream commit 43a51019cc8ff1b1cd2ba72e86563beb40d356fc ]

Make sure to search only the child nodes of "/clocks", rather than the
whole device-tree depth-first starting at "/clocks" when determining
whether to register a fixed clock in the legacy board-clock registration
helper.

Fixes: ee15faff ("clk: qcom: common: Add API to register board clocks backwards compatibly")
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>