ahci: remove packed attribute from register structure

It cause per-byte access instead of 32 bit on GCC/riscv64 that breaks operation.

All fields are 32 bit so alignment is already fine and packing is not needed.

Change-Id: Ie96eac6615c9326e84608be1c667bc5d3600c508
Reviewed-on: https://review.haiku-os.org/c/haiku/+/4117
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>

src/add-ons/kernel/busses/scsi/ahci/ahci_defs.h

@@ -129,7 +129,7 @@ typedef struct {
 	uint32		devslp;			// Device Sleep
 	uint32		res[10];		// Reserved
 	uint32		vendor[4];		// Vendor Specific
-} _PACKED ahci_port;
+} ahci_port;
 
 
 enum {