ARM: defconfig: remove stale CONFIG_ZBOOT_ROM entries

The default is always 0x0 after commit 39c3e304 ("ARM: 8984/1:
Kconfig: set default ZBOOT_ROM_TEXT/BSS value to 0x0"), so any
defconfig file that has these two lines can now drop them to reduce
the diff against the 'make savedefconfig' version.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Sudeep Holla <sudeep.holla@arm.com>
Acked-by: Gregory CLEMENT <gregory.clement@bootlin.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>