net: xilinx: axienet: Get coalesce parameters from driver state

The cr variables now contain the same values as the control registers
themselves. Extract/calculate the values from the variables instead of
saving the user-specified values. This allows us to remove some
bookeeping, and also lets the user know what the actual coalesce
settings are.

Signed-off-by: Sean Anderson <sean.anderson@linux.dev>
Reviewed by: Shannon Nelson <shannon.nelson@amd.com>
Link: https://patch.msgid.link/20250206201036.1516800-4-sean.anderson@linux.dev


Signed-off-by: Jakub Kicinski <kuba@kernel.org>