RISC-V: Rename CONFIG_CMDLINE_OVERRIDE to CONFIG_CMDLINE_FORCE

The device tree code looks for CONFIG_CMDLINE_FORCE, but we were using
CONFIG_CMDLINE_OVERRIDE.  It looks like this was just a hold over from
before our device tree conversion -- in fact, we'd already removed the
support for CONFIG_CMDLINE_OVERRIDE from our arch-specific code so it
didn't even work any more.

Thanks to Mortiz and Trung for finding the original bug, and for Michael
for suggeting a better fix.

CC: Trung Tran <trung.tran@ettus.com>
CC: Michael J Clark <mjc@sifive.com>
Reviewed-by: NMoritz Fischer <mdf@kernel.org>
Signed-off-by: NPalmer Dabbelt <palmer@sifive.com>

arch/riscv/Kconfig

@@ -289,7 +289,7 @@ config CMDLINE_BOOL
 	  in CONFIG_CMDLINE.
 
 	  The built-in options will be concatenated to the default command
-	  line if CMDLINE_OVERRIDE is set to 'N'. Otherwise, the default
+	  line if CMDLINE_FORCE is set to 'N'. Otherwise, the default
 	  command line will be ignored and replaced by the built-in string.
 
 config CMDLINE
@@ -299,7 +299,7 @@ config CMDLINE
 	help
 	  Supply command-line options at build time by entering them here.
 
-config CMDLINE_OVERRIDE
+config CMDLINE_FORCE
 	bool "Built-in command line overrides bootloader arguments"
 	depends on CMDLINE_BOOL
 	help