[LIBS] Radix tree library missing the "vmm_compiler" header inclusion

Since the radix tree library is using "likely", an inclusion to vmm_compiler is
necessary.

Signed-off-by: Jimmy Durand Wesolowski <jimmy.durand-wesolowski@openwide.fr>
[CORE] Correcting warnings on "vmm_devdrv_get_data" argument.

Some functions are passing a constant vmm_device structure argument to
"vmm_devdrv_get_data", leading to warnings. As this function does not modify
its argument, this patch defines the argument as constant.

Signed-off-by: Jimmy Durand Wesolowski <jimmy.durand-wesolowski@openwide.fr>
[CORE] Add casting on the tested pointer in the "VMM_IS_ERR_VALUE" macro.

As we test pointers with "VMM_IS_ERR_VALUE", the argument should be cast to
an unsigned long before the test with "VMM_MAX_ERRNO".

Signed-off-by: Jimmy Durand Wesolowski <jimmy.durand-wesolowski@openwide.fr>
[DRIVERS] clk: move bcm2835 clk driver to its own directory

Signed-off-by: Jean-Christophe Dubois <jcd@tribudubois.net>
[DRIVERS] clk: move i.MX clk driver to drivers/clk directory

Signed-off-by: Jean-Christophe Dubois <jcd@tribudubois.net>