ARM: i.MX: system.c: Convert goto to if statement

Using goto here doesn't bring any advantages and only makes the code
flow less clear. No functional changes.

Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>