RISC-V: Fix indentation of "length" attribute for branches and jumps

RISC-V: Fix indentation of "length" attribute for branches and jumps

The "length" attribute calculation expressions for branches and jumps
are incorrectly and misleadingly indented, and they overrun the 80
column limit as well, all of this causing troubles in following them.
Correct all these issues.

	gcc/
	* config/riscv/riscv.md (length): Fix indentation for branch and
	jump length calculation expressions.