Documentation: Fix markdown highlighting

Fix some code blocks that use invalid Markdown syntax.

Change-Id: I8cfe63b2c21ae93923f88bbf7ef4cfb8dccdb5ef
Signed-off-by: Patrick Rudolph <siro@das-labor.org>
Reviewed-on: https://review.coreboot.org/29207
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Philipp Deppenwiese <zaolin.daisuki@gmail.com>

Documentation/soc/cavium/cn81xx/index.md

@@ -41,8 +41,8 @@ or romstage until DRAM has been set up. At the end of romstage the cachelines
 are unlocked and the contents are flushed to DRAM.
 Locked cachelines are never evicted.
 
-The CAR setup is done in '''bootblock_custom.S''' and thus doesn't use the common
-aarch64 '''bootblock.S''' code.
+The CAR setup is done in `bootblock_custom.S` and thus doesn't use the common
+aarch64 `bootblock.S` code.
 
 ## DRAM setup
 

Documentation/vendorcode/cavium/bdk.md

@@ -1,7 +1,7 @@
 # Cavium's BDK
 
 ## BDK
-A part of Cavium's BDK can be found in '''src/vendorcode/cavium/bdk'''.
+A part of Cavium's BDK can be found in `src/vendorcode/cavium/bdk`.
 It does the **DRAM init** in romstage and the **PCIe**, **QLM**, **SLI**,
 **PHY**, **BGX**, **SATA** init in ramstage.
 
@@ -11,9 +11,9 @@ compatible. The devicetree stores key-value pairs (see **bdk-devicetree.h**
 for implementation details), where the key and the value are stored as strings.
 
 The key-value pairs must be advertised in romstage and ramstage using the
-'''bdk_config_set_fdt()''' method.
+`bdk_config_set_fdt()` method.
 
-The tool '''util/cavium/devicetree_convert.py''' can be used to convert a
+The tool `util/cavium/devicetree_convert.py` can be used to convert a
 devicetree to a key-value array.
 
 ## Modifications