rk3288: Disable ramstage compression by default

The ramstage is loaded from romstage, so the LZMA scratchpad buffer used
to decompress it is part of the romstage BSS in SRAM. On RK3288, SRAM
cannot be cached which makes the decompression so slow that it's faster
to just load an uncompressed image from SPI. Disable ramstage
compression on this SoC to account for that.

Since Kconfig is weird and we cannot disable an option that is enabled
by default with 'select', we need to rearrange menu groups so that
'mainboard' and 'chipset' come before 'General setup', which allows the
subdirectory Kconfig files sourced by them to override the generic
defaults specified later.

BRANCH=None
BUG=None
TEST=Built for Pinky and Falco, confirmed that the former didn't have
COMPRESS_RAMSTAGE in its .config and the latter still did. Measured a
speed-up of about 35ms on Pinky. (For some weird reason, the
decompression of the payload also takes way longer than on other
platforms, although not as long as the ramstage. I have no explanation
for that and can't really think of a good way to figure it out... maybe
the Cortex-A12 is just terrible at some operation that LZMA uses a lot?)

Change-Id: I9f67f7537696ec09496483b16b59a8b73f4cb11b
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/234192
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

src/soc/rockchip/rk3288/Kconfig

@@ -40,4 +40,11 @@ config BOOTBLOCK_CPU_INIT
 	string
 	default "soc/rockchip/rk3288/bootblock.c"
 
+config COMPRESS_RAMSTAGE
+	bool "Compress ramstage with LZMA"
+	default n
+	help
+	  The ramstage is loaded from code running in uncached SRAM, you
+	  probably don't want LZMA running on that.
+
 endif