clk: bcm: rpi: Assign ->num before accessing ->hws

Commit f316cdff ("clk: Annotate struct clk_hw_onecell_data with
__counted_by") annotated the hws member of 'struct clk_hw_onecell_data'
with __counted_by, which informs the bounds sanitizer about the number
of elements in hws, so that it can warn when hws is accessed out of
bounds. As noted in that change, the __counted_by member must be
initialized with the number of elements before the first array access
happens, otherwise there will be a warning from each access prior to the
initialization because the number of elements is zero. This occurs in
raspberrypi_discover_clocks() due to ->num being assigned after ->hws
has been accessed:

  UBSAN: array-index-out-of-bounds in drivers/clk/bcm/clk-raspberrypi.c:374:4
  index 3 is out of range for type 'struct clk_hw *[] __counted_by(num)' (aka 'struct clk_hw *[]')

Move the ->num initialization to before the first access of ->hws, which
clears up the warning.

Cc: stable@vger.kernel.org
Fixes: f316cdff

 ("clk: Annotate struct clk_hw_onecell_data with __counted_by")
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/r/20240425-cbl-bcm-assign-counted-by-val-before-access-v1-2-e2db3b82d5ef@kernel.org
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>