ARM: clps711x: Remove EP72XX_ROM_BOOT option

CLPS711X CPUs have 128 bytes of on-chip Boot ROM with an
instruction sequence that configure UART1 to receive up to
2 Kbytes of serial data which is then placed in the on-chip
SRAM. Once the download is complete, the program counter
jumps to SRAM to begin executed the downloaded data.
The purpose of this mode is to allow the downloaded code to
facilitate programming of FLASH or other ROM device. Selection
of the internal Boot ROM is accomplished at power-on-reset time.
No reason to keep this special (develop only) mode in the kernel.
This patch removes EP72XX_ROM_BOOT kernel symbol.

Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>