clk: ast2600: Fix AHB clock divider for A1

clk: ast2600: Fix AHB clock divider for A1

[ Upstream commit 2d491066ccd4286538450c227fc5094ceb04b494 ]

The latest specs for the AST2600 A1 chip include some different bit
definitions for calculating the AHB clock divider. Implement these in
order to get the correct AHB clock value in Linux.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
Link: https://lkml.kernel.org/r/20200408203616.4031-1-eajames@linux.ibm.com
Fixes: d3d04f6c330a ("clk: Add support for AST2600 SoC")
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>