ARC: [TB10x] Adapt device tree to new compatible string

The original device tree was written using a slightly different
implementation of the fixed-factor-clock device tree binding. The
compatible string must be modified in order to be compatible with the
new implementation.

Signed-off-by: Christian Ruppert <christian.ruppert@abilis.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>