udf: fs/udf/partition.c:udf_get_pblock() mustn't be inline

This patch fixes the following build error with UML and gcc 4.3:

<--  snip  -->

...
  CC      fs/udf/partition.o
/home/bunk/linux/kernel-2.6/git/linux-2.6/fs/udf/partition.c: In function ‘udf_get_pblock_virt15’:
/home/bunk/linux/kernel-2.6/git/linux-2.6/fs/udf/partition.c:32: sorry, unimplemented: inlining failed in call to ‘udf_get_pblock’: function body not available
/home/bunk/linux/kernel-2.6/git/linux-2.6/fs/udf/partition.c:102: sorry, unimplemented: called from here
make[3]: *** [fs/udf/partition.o] Error 1

<--  snip  -->

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Jan Kara <jack@suse.cz>