Fix the following build errors:
irq_32.c:258:7: error: array subscript [16, 79] is outside array bounds of 'struct tt_entry[1]
irq_32.c:271:14: error: assignment to 'struct tt_entry *' from incompatible pointer type 'struct tt_entry (*)[]

trapbase is a pointer to an array of tt_entry, but the code declared it
as a pointer so the compiler see a single entry and not an array.
Fix this by modifyinf the declaration to be an array, and modify all
users to take the address of the first member.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org> # build-tested
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: "David S. Miller" <davem@davemloft.net>
Reviewed-by: Andreas Larsson <andreas@gaisler.com>
Tested-by: Andreas Larsson <andreas@gaisler.com>
Signed-off-by: Andreas Larsson <andreas@gaisler.com>
Link: https://lore.kernel.org/r/20240224-sam-fix-sparc32-all-builds-v2-2-1f186603c5c4@ravnborg.org