memory: pl353: fix mask of ECC page_size config register

The mask for page size of ECC Configuration Register should be 0x3,
according to  the datasheet of PL353 smc.

Fixes: fee10bd2 ("memory: pl353: Add driver for arm pl353 static memory controller")
Signed-off-by: gexueyuan <gexueyuan@gmail.com>
Link: https://lore.kernel.org/r/20210331031056.5326-1-gexueyuan@gmail.com


Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>