csky: change a Kconfig symbol name to fix e1000 build error

e1000's #define of CONFIG_RAM_BASE conflicts with a Kconfig symbol in
arch/csky/Kconfig.

The symbol in e1000 has been around longer, so change arch/csky/ to use
DRAM_BASE instead of RAM_BASE to remove the conflict.  (although e1000
is also a 2-line change)

Link: https://lkml.kernel.org/r/20210411055335.7111-1-rdunlap@infradead.org


Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reported-by: kernel test robot <lkp@intel.com>
Acked-by: Guo Ren <guoren@kernel.org>
Cc: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>