ARMv7-R: add new Kconfig entries for d/i-cache

Unlike in ARMv7-A/M, Kconfig entries for data and instruction caches
are currently missing in ARMv7-R. This commit adds those missing Kconfig
entries. Actual implmenetation for those functions will be added in the
subsequent patches.

Signed-off-by: Heesub Shin <heesub.shin@samsung.com>