disk/i386/pc/biosdisk: Read up to 63 sectors in LBA mode

Current code imposes limitations on the amount of sectors read in
a single call according to CHS layout of the disk even in LBA
read mode. There's no need to obey CHS layout restrictions for
LBA reads on LBA disks. It only slows down booting process.

See: https://lore.kernel.org/grub-devel/d42a11fa-2a59-b5e7-08b1-d2c60444bb99@valdikss.org.ru/

Signed-off-by: ValdikSS <iam@valdikss.org.ru>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

grub-core/disk/i386/pc/biosdisk.c

@@ -471,7 +471,7 @@ grub_biosdisk_rw (int cmd, grub_disk_t disk,
       struct grub_biosdisk_dap *dap;
 
       dap = (struct grub_biosdisk_dap *) (GRUB_MEMORY_MACHINE_SCRATCH_ADDR
-					  + (data->sectors
+					  + (GRUB_DISK_MAX_LBA_SECTORS
 					     << disk->log_sector_size));
       dap->length = sizeof (*dap);
       dap->reserved = 0;
@@ -561,6 +561,9 @@ get_safe_sectors (grub_disk_t disk, grub_disk_addr_t sector)
   struct grub_biosdisk_data *data = disk->data;
   grub_uint32_t sectors = data->sectors;
 
+  if (data->flags & GRUB_BIOSDISK_FLAG_LBA)
+    sectors = GRUB_DISK_MAX_LBA_SECTORS;
+
   /* OFFSET = SECTOR % SECTORS */
   grub_divmod64 (sector, sectors, &offset);