clk: imx8mq: Correct the pcie1 sels

- The sys2_pll_50m should be one of the clock sels of PCIE_AUX clock.
Change the sys2_pll_500m to sys2_pll_50m.
- Correct one misspell of the imx8mq_pcie1_ctrl_sels definition, from
"sys2_pll_250m" to "sys2_pll_333m".

Signed-off-by: Richard Zhu <hongxing.zhu@nxp.com>
Signed-off-by: Abel Vesa <abel.vesa@nxp.com>