Update Linux to v5.4.148

Sourced from [1]

[1] https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.4.148.tar.gz

Change-Id: Ib3d26c5ba9b022e2e03533005c4fed4d7c30b61b
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
diff --git a/arch/csky/mm/init.c b/arch/csky/mm/init.c
index d4c2292..00e9627 100644
--- a/arch/csky/mm/init.c
+++ b/arch/csky/mm/init.c
@@ -31,6 +31,7 @@
 
 pgd_t swapper_pg_dir[PTRS_PER_PGD] __page_aligned_bss;
 pte_t invalid_pte_table[PTRS_PER_PTE] __page_aligned_bss;
+EXPORT_SYMBOL(invalid_pte_table);
 unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)]
 						__page_aligned_bss;
 EXPORT_SYMBOL(empty_zero_page);