target-mips: Clean up other_cpu in helper_{d,e}vpe()

Free the variable name "other_cpu" for later use for MIPSCPU.

Fix off-by-one indentation while at it.

Signed-off-by: Andreas Färber <afaerber@suse.de>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
