xen/arm: introduce bootcmdlines

xen/arm: introduce bootcmdlines

Introduce a new array to store the cmdline of each boot module. It is
separate from struct bootmodules. Remove the cmdline field from struct
boot_module. This way, kernels and initrds with the same address in
memory can share struct bootmodule (important because we want them to be
free'd only once), but they can still have their separate bootcmdline
entries.

Add a dt_name field to struct bootcmdline to make it easier to find the
correct entry. Store the name of the "xen,domain" compatible node (for
example "Dom1"). This is a better choice compared to the name of the
"multiboot,kernel" compatible node, because their names are not unique.
For instance there can be more than one "module@0x4c000000" in the
system, but there can only be one "/chosen/Dom1".

Add a pointer to struct kernel_info to point to the cmdline for a given
kernel.

Signed-off-by: Stefano Stabellini <stefanos@xilinx.com>
Acked-by: Julien Grall <julien.grall@arm.com>