memory: tegra: replace DEFINE_SIMPLE_ATTRIBUTE with DEFINE_DEBUGFS_ATTRIBUTE

Fix the following coccicheck warning:

  drivers/memory/tegra/tegra124-emc.c:1207:0-23: WARNING:
    tegra_emc_debug_min_rate_fops should be defined with DEFINE_DEBUGFS_ATTRIBUTE

Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Link: https://lore.kernel.org/r/1614243958-55847-1-git-send-email-yang.lee@linux.alibaba.com


Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>