efi_loader: allow EFI_LOADER_BOUNCE_BUFFER on all architectures

There not only ARM64 boards but also RISC-V boards that require a bounce
buffer to read block devices.

Drop the architecture restriction.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
diff --git a/lib/efi_loader/Kconfig b/lib/efi_loader/Kconfig
index 1179c31..6ffefa9 100644
--- a/lib/efi_loader/Kconfig
+++ b/lib/efi_loader/Kconfig
@@ -364,7 +364,6 @@
 
 config EFI_LOADER_BOUNCE_BUFFER
 	bool "EFI Applications use bounce buffers for DMA operations"
-	depends on ARM64
 	help
 	  Some hardware does not support DMA to full 64bit addresses. For this
 	  hardware we can create a bounce buffer so that payloads don't have to