clk: imx: pllv1: fix kernel-doc notation for struct clk_pllv1

clk: imx: pllv1: fix kernel-doc notation for struct clk_pllv1

Convert struct clk_pllv1 comments to kernel-doc notation and move them
below the MFN_* macros.

Fixes this kernel-doc warning:

drivers/clk/imx/clk-pllv1.c:12: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
    * pll v1

Fixes: bb6941ca739a ("ARM i.MX: Add common clock support for pllv1")
Fixes: 77669af4d57e ("ARM: imx: pllv1: Fix PLL calculation for i.MX27")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reported-by: kernel test robot <lkp@intel.com>
Cc: Abel Vesa <abel.vesa@nxp.com>
Cc: linux-clk@vger.kernel.org
Cc: linux-imx@nxp.com
Cc: Alexander Shiyan <shc_work@mail.ru>
Cc: Shawn Guo <shawn.guo@linaro.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Link: https://lore.kernel.org/r/20211115032607.28970-1-rdunlap@infradead.org
Signed-off-by: Stephen Boyd <sboyd@kernel.org>