Fix warning: this statement may fall through [-Wimplicit-fallthrough=]

[sirlucjan]

In a previous pull request I forgot to fix the following warning

CC mm/uksm.o
mm/uksm.c: In function 'uksm_memory_callback':
mm/uksm.c:4835:72: warning: this statement may fall through [-Wimplicit-fallthrough=]
 4835 | mn->start_pfn + mn->nr_pages)) != NULL)
mm/uksm.c:4839:9: note: here
 4839 | case MEM_CANCEL_OFFLINE:
      | ^~~~

A simple change was enough to eliminate the problem.

 CC [M] fs/nls/nls_koi8-ru.o
  CC [M] fs/nls/nls_utf8.o
  CC mm/uksm.o
  CC [M] fs/nls/mac-celtic.o
  CC arch/x86/kernel/cpu/sgx/ioctl.o
  CC kernel/time/hrtimer.o
  CC [M] fs/nls/mac-centeuro.o
  CC [M] fs/nls/mac-croatian.o
  CC [M] fs/nls/mac-cyrillic.o
  CC arch/x86/kernel/cpu/sgx/main.o
  CC [M] fs/nls/mac-gaelic.o
  CC kernel/time/timekeeping.o
  CC [M] fs/nls/mac-greek.o
  CC [M] fs/nls/mac-iceland.o
  CC arch/x86/kernel/cpu/sgx/virt.o
  CC [M] fs/nls/mac-inuit.o
  CC [M] fs/nls/mac-romanian

Signed-off-by: Piotr Gorski lucjan.lucjanov@gmail.com

[dolohow]

Thanks a lot