regmap: rbtree: Use alloc_flags for memory allocations

regmap: rbtree: Use alloc_flags for memory allocations

The kunit tests discovered a sleeping in atomic bug.  The allocations
in the regcache-rbtree code should use the map->alloc_flags instead of
GFP_KERNEL.

[    5.005510] BUG: sleeping function called from invalid context at include/linux/sched/mm.h:306
[    5.005960] in_atomic(): 1, irqs_disabled(): 128, non_block: 0, pid: 117, name: kunit_try_catch
[    5.006219] preempt_count: 1, expected: 0
[    5.006414] 1 lock held by kunit_try_catch/117:
[    5.006590]  #0: 833b9010 (regmap_kunit:86:(config)->lock){....}-{2:2}, at: regmap_lock_spinlock+0x14/0x1c
[    5.007493] irq event stamp: 162
[    5.007627] hardirqs last  enabled at (161): [<80786738>] crng_make_state+0x1a0/0x294
[    5.007871] hardirqs last disabled at (162): [<80c531ec>] _raw_spin_lock_irqsave+0x7c/0x80
[    5.008119] softirqs last  enabled at (0): [<801110ac>] copy_process+0x810/0x2138
[    5.008356] softirqs last disabled at (0): [<00000000>] 0x0
[    5.008688] CPU: 0 PID: 117 Comm: kunit_try_catch Tainted: G                 N 6.4.4-rc3-g0e8d2fdfb188 #1
[    5.009011] Hardware name: Generic DT based system
[    5.009277]  unwind_backtrace from show_stack+0x18/0x1c
[    5.009497]  show_stack from dump_stack_lvl+0x38/0x5c
[    5.009676]  dump_stack_lvl from __might_resched+0x188/0x2d0
[    5.009860]  __might_resched from __kmem_cache_alloc_node+0x1dc/0x25c
[    5.010061]  __kmem_cache_alloc_node from kmalloc_trace+0x30/0xc8
[    5.010254]  kmalloc_trace from regcache_rbtree_write+0x26c/0x468
[    5.010446]  regcache_rbtree_write from _regmap_write+0x88/0x140
[    5.010634]  _regmap_write from regmap_write+0x44/0x68
[    5.010803]  regmap_write from basic_read_write+0x8c/0x270
[    5.010980]  basic_read_write from kunit_try_run_case+0x48/0xa0

Fixes: 28644c809f44 ("regmap: Add the rbtree cache support")
Reported-by: Guenter Roeck <linux@roeck-us.net>
Closes: https://lore.kernel.org/all/ee59d128-413c-48ad-a3aa-d9d350c80042@roeck-us.net/
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/58f12a07-5f4b-4a8f-ab84-0a42d1908cb9@moroto.mountain
Signed-off-by: Mark Brown <broonie@kernel.org>