opensbi: bump to 1.7

opensbi: bump to 1.7

This release has:
- New parameter in top-level Makefile for reproducible builds
- Added MIPS P8700 platform support
- Allow arbitrary path in LLVM parameter of top-level Makefile
- Improved SBI v3.0 extensions to match frozen specification
-  Emulate AMO instructions when Zaamo is not available
- Stop the harts waiting for HSM start from supervisor software
- Improved generic platform overrides to use common fdt_driver helpers
- Improved SBI MPXY framework to use per-domain data
- Added support for control transfer records (CTR) ISA extension
- Use LR and SC when Zaamo ISA extension is not available
- Added PXA UART support
- Added support for double-trap ISA extensions
- Optimized hartid and scratch lookup
- Added unit tests for bitwise operations
- Added unit tests for SBI ecall functionality
- Constify various FDT driver definitions
- Added MPXY RPMI mailbox driver for System MSI service group
- Improved RPMI drivers to match frozen specifications
- Initialize miscellaneous early drivers in one pass
- Use fdt_driver helpers for irqchip driver framework
- Allow adding SSE events dynamically at boot-time
- Simple singly linked list implementation

Overall, this release adds more ISA extensions and does many device driver
improvements.

Signed-off-by: Thomas Perrot <thomas.perrot@bootlin.com>
Signed-off-by: Antonin Godard <antonin.godard@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>