ARM: exynos: add missing of_node_put for loop iteration

Early exits from for_each_compatible_node() should decrement the
node reference counter.  Reported by Coccinelle:

  arch/arm/mach-exynos/exynos.c:52:1-25: WARNING:
    Function "for_each_compatible_node" should have of_node_put() before break around line 58.

Fixes: b3205dea

 ("ARM: EXYNOS: Map SYSRAM through generic DT bindings")
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20210425174945.164612-1-krzysztof.kozlowski@canonical.com