arm: npcm: enable L2 cache in NPCM7xx architecture

arm: npcm: enable L2 cache in NPCM7xx architecture

This patch Enable ARM L2 cache module in Nuvoton NPCM7xx BMC
by adding L2 cache parameters into NPCM7xx DT machine start structure.

At patch V7 arm: npcm: add basic support for Nuvoton BMCs we got comments
regarding the flags use in L2 cache module.
- https://www.spinics.net/lists/arm-kernel/msg613212.html

After checking again the L2 cache use in the NPCM7xx,
the only L2 cache flag we need to set is L2C_AUX_CTRL_SHARED_OVERRIDE
and it is done in the device tree:
https://patchwork.kernel.org/patch/10063497/

L2 cache flag mask allowed all the flag option.

Signed-off-by: Tomer Maimon <tmaimon77@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>