s390/kexec: fix memory leak of ipl report buffer

unreferenced object 0x38000195000 (size 4096):
  comm "kexec", pid 8548, jiffies 4294953647 (age 32443.270s)
  hex dump (first 32 bytes):
    00 00 00 c8 20 00 00 00 00 00 00 c0 02 80 00 00  .... ...........
    40 40 40 40 40 40 40 40 00 00 00 00 00 00 00 00  @@@@@@@@........
  backtrace:
    [<0000000011a2f199>] __vmalloc_node_range+0xc0/0x140
    [<0000000081fa2752>] vzalloc+0x5a/0x70
    [<0000000063a4c92d>] ipl_report_finish+0x2c/0x180
    [<00000000553304da>] kexec_file_add_ipl_report+0xf4/0x150
    [<00000000862d033f>] kexec_file_add_components+0x124/0x160
    [<000000000d2717bb>] arch_kexec_kernel_image_load+0x62/0x90
    [<000000002e0373b6>] kimage_file_alloc_init+0x1aa/0x2e0
    [<0000000060f2d14f>] __do_sys_kexec_file_load+0x17c/0x2c0
    [<000000008c86fe5a>] __s390x_sys_kexec_file_load+0x40/0x50
    [<000000001fdb9dac>] __do_syscall+0x1bc/0x1f0
    [<000000003ee4258d>] system_call+0x78/0xa0

Signed-off-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Philipp Rudo <prudo@redhat.com>
Fixes: 99feaa71 ("s390/kexec_file: Create ipl report and pass to next kernel")
Cc: <stable@vger.kernel.org> # v5.2: 20c76e24: s390/kexec: fix return code handling
Cc: <stable@vger.kernel.org> # v5.2
Link: https://lore.kernel.org/r/20211116033101.GD21646@MiWiFi-R3L-srv


Signed-off-by: Heiko Carstens <hca@linux.ibm.com>