mmc: s3mci: mark debug_regs[] as static

The global array clashes with a newly added symbol of the same name:

drivers/staging/ccree/cc_debugfs.o:(.data+0x0): multiple definition of `debug_regs'
drivers/mmc/host/s3cmci.o:(.data+0x70): first defined here

We should fix both, this one addresses the s3cmci driver by removing
the symbol from the global namespace. While at it, this separates
the declaration from the type definition and makes the variable const.

Fixes: 9bdd203b ("s3cmci: add debugfs support for examining driver and hardware state")
Fixes: b3ec9a67

 ("staging: ccree: staging: ccree: replace sysfs by debugfs interface")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>