arm: mvebu: a38x: Fix 5200000 baudrate

arm: mvebu: a38x: Fix 5200000 baudrate

Fix baudrate value 5150000 which was added in commit ead4864fa6cc ("arm:
mvebu: a38x: Define supported UART baudrates").

Exact value for divisor 3 with 250 MHz TCLK is 5208333 baudrate. In above
commit I incorrectly rounded it to 5150000 value due to testing with
USB-UART hw which incorrectly reported exact value and divisor configured
on other other end of UART link.

Fix this value to 520000 baudrate which is more close to the exact hardware
value and also has less fraction parts.

Signed-off-by: Pali Rohár <pali@kernel.org>
Fixes: ead4864fa6cc ("arm: mvebu: a38x: Define supported UART baudrates")
Reviewed-by: Stefan Roese <sr@denx.de>