mmc: stm32_sdmmc2: Increase SDMMC_BUSYD0END_TIMEOUT_US

mmc: stm32_sdmmc2: Increase SDMMC_BUSYD0END_TIMEOUT_US

Increase SDMMC_BUSYD0END_TIMEOUT_US from 1s to 2s to
avoid timeout error during blocks erase on some sdcard

Issue seen on Kingston 16GB :
  Device: STM32 SDMMC2
  Manufacturer ID: 27
  OEM: 5048
  Name: SD16G
  Bus Speed: 50000000
  Mode: SD High Speed (50MHz)
  card capabilities: widths [4, 1] modes [SD Legacy, SD High Speed (50MHz)]
  host capabilities: widths [4, 1] modes [MMC legacy, SD Legacy, MMC High Speed (26MHz), SD High Speed (50MHz), MMC High Speed (52MHz)]
  Rd Block Len: 512
  SD version 3.0
  High Capacity: Yes
  Capacity: 14.5 GiB
  Bus Width: 4-bit
  Erase Group Size: 512 Bytes

Issue reproduced with following command:

STM32MP> mmc erase 0 100000

MMC erase: dev # 0, block # 0, count 1048576 ... mmc erase failed
16384 blocks erased: ERROR

By setting SDMMC_BUSYD0END_TIMEOUT_US at 2 seconds and by adding
time measurement in stm32_sdmmc2_end_cmd() as shown below:

	+start = get_timer(0);
	/* Polling status register */
	ret = readl_poll_timeout(priv->base + SDMMC_STA,
				 status, status & mask,
 				 SDMMC_BUSYD0END_TIMEOUT_US);

	+printf("time = %ld ms\n", get_timer(start));

We get the following trace:

STM32MP> mmc erase 0  100000

MMC erase: dev # 0, block # 0, count 1048576 ...
time = 17 ms
time = 1 ms
time = 1025 ms
time = 54 ms
time = 56 ms
time = 1021 ms
time = 57 ms
time = 56 ms
time = 1020 ms
time = 53 ms
time = 57 ms
time = 1021 ms
time = 53 ms
time = 57 ms
time = 1313 ms
time = 54 ms
time = 56 ms
time = 1026 ms
time = 54 ms
time = 56 ms
time = 1036 ms
time = 54 ms
time = 56 ms
time = 1028 ms
time = 53 ms
time = 56 ms
time = 1027 ms
time = 54 ms
time = 56 ms
time = 1024 ms
time = 54 ms
time = 56 ms
time = 1020 ms
time = 54 ms
time = 57 ms
time = 1023 ms
time = 54 ms
time = 56 ms
time = 1033 ms
time = 53 ms
time = 57 ms
....
time = 53 ms
time = 57 ms
time = 1021 ms
time = 56 ms
time = 56 ms
time = 1026 ms
time = 54 ms
time = 56 ms
1048576 blocks erased: OK

We see that 1 second timeout is not enough, we also see one measurement
up to 1313 ms. Set the timeout to 2 second to keep a security margin.

Signed-off-by: Patrice Chotard <patrice.chotard@st.com>